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Title: support material for class 11
Description: detailed explanation with practice questions and solutions
Description: detailed explanation with practice questions and solutions
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COURSE STRUCTURE
Class XI (Theory)
One Paper
Unit No
...
70
UNIT-1
SOME BASIC CONCEPTS OF CHEMISTRY
Law of conservation of mass : ‘Mass can neither be created nor destroyed
...
Law of constant composition : A chemical compound is always found to
be made of same elements combined together in the same fixed ratio by mass
...
Gram atomic mass or molar mass of an element is mass of 1 mol of
atoms or atomic mass expressed in grams
...
Molar mass of an
element is also called one gram atom
...
For example,
molecular mass of CO2 in 44 u, therefore, molar mass of CO2 is 44 grams/mol
...
Molar mass and standard molar volume of gaseous substances :
1 mole of any gas occupies a volume of 22
...
e
...
If standard pressure is taken as 1 bar, then the standard molar volume is
taken as 22
...
W 1000
Molarity (M) B
M B VmL
WB 1000
Molality (m)
M B WA
nB
For binary solutions : Mole fraction (X B ) of solute
nA nB
XA = 1 XB
where
XA = mole fraction of solvent,
XB = mol fraction of solute
WA = mass of solvent
WB = Mass of solute
MB = Molar mass of solute
VmL = Volume of solution in mL
[XI – Chemistry]
2
Dilution Formula : M1V1 = M2V2
Where : M1 = Molarity of concentrated solution
V1
= Volume of concentrated solution
M2 = Molarity of dilute solution
V2
= Volume of dilute solution
For a general chemical equation : aA + bB cC + dD
b mol of B
a mol of A
Example : Calculate the volume of 0
...
1 g of P4O6 in water
...
1g P 4O 6
220g P4 O 6
mol of NaOH 0
...
5 10 mol P O
4
6
4 mol H 3 PO3 2 mol NaOH
1 mol P4 O6 1 mol H3 PO3
= 4 102 mol NaOH
Volume of NaOH solution in litres 4102 mol NaOH
1 L NaOH solution
0
...
4 L
1- MARK QUESTIONS
1
...
Liquids take the shape of the container in which they are placed
...
Give two examples of a homogeneous mixture
...
Calculate the number of molecules present in 100
...
5
...
0 g CO2
...
Write the SI unit of temperature
...
Define law of multiple proportions
...
N2 and H2 combine according to the following equation :
N 2 ( g ) 3H 2 ( g ) 2NH 3 ( g )
If 100 mL of N2 gas combines with 300 mL of N2 gas, calculate the volume
of NH3 produced at same temperature and pressure
...
10
...
12
...
14
...
16
...
18
19
...
21
...
23
...
Out of 1 M NaCl solution and 1 m NaCl solution, which one is more concentrated ?
Write the S
...
unit of Avogadro constant
...
0 g C is burnt in excess oxygen ?
Molarity is temperature dependent but molality is not
...
2 mol
Calculate the mole fraction of N2 when 28 g N2 is mixed with 64 g O2 gas
...
: 0
...
0 ppm (by mass) Cl2 present in it
...
(Density of water = 1
...
)
Calculate the number of electrons in 17
...
Calculate the number of atoms present in 64
...
If the density of 68% nitric acid solution is 1
...
0 L solution
...
5 M Na2CO3 solution in grams per litre
...
0 g sample
...
20
Which of the following has highest mass ?
(a) 32 g O2 gas
(b) 2 g atom of Cl2
(c) 0
...
03 1023 atoms of C
How many moles of methane are required to produce 22
...
2
...
4
...
(Given
molar mass NaCl = 58
...
0
How much CO2 is produced when 1
...
0 g
oxygen ?
0
...
[XI – Chemistry]
4
5
...
7
...
9
...
11
...
13
...
15
...
Pure oxygen is prepared by thermal decomposition of KClO3 according to
the equation :
3
KClO3 ( s) KCl (s ) O2 (g )
2
Calculate the volume of oxygen gas liberated at STP by heating 12
...
Classify the following as pure substance or mixture ?
(a) Ethyl alcohol
(b) Blood
(c) 22 carat gold
(d) Air
How many significant figures are present in the answer of following
calculations :
0
...
15 0
...
0125 + 0
...
023
(b)
0
...
0 g H2 (g)
(b) 1
...
0 g CH3OH (l)
(d) 1
...
9 and 30
...
Molar mass of
this oxide is 170
...
[Ans
...
Calculate molality of
The density of 3 M solution of NaCl is 1
...
(Molar mass of NaCl is 58
...
Calculate the molarity of an aqueous solution of methanol in which the
mole fraction of ethanol is 0
...
Assume the density of water to be 1
...
[Ans
...
0 g MnO2 according to the equation :
4HCl (aq) + MnO2 (s) 2H2O (l) + MnCl2 (aq) + Cl2 (g)
[ Ans
...
40 g]
How are 0
...
5 M Na2CO3 are different from each other?
If mass of air at sea level is 1034 g cm2, calculate the pressure in pascal
...
8 ms2, 1 Pa = 1 Nm2)
[Ans
...
01332 105 Pa]
A polluted water sample has been found (CH 3) to have 15 ppm CHCl3 in it
...
(b) Determine the molality of chloroform (CHCl3) in the water sample
...
:
(a) = ~ 15 × 10–4 g
(b) = 1
...
96755 g mol1
37
...
9624 g mol1
0
...
063%
99
...
: 39
...
If the speed of light is 3
...
00 ns
...
: 0
...
State the law of definite proportions
...
19
...
38 g CO2 and 0
...
A volume of 10L (measured at STP) of this hydrocarbon weighs 11
...
Calculate the molecular formula of this hydrocarbon
...
: C2 H2]
20
...
(a) State and explain Avogadro’s law
...
(b) 10
...
6 g at STP
...
[Ans
...
0 g/mol]
2
...
75 M HCl
...
: 0
...
[Ans
...
21 L]
Dinitrogen and dihydrogen react with each other to produce ammonia according to following chemical equation :
N2 (g) + 3H2 (g) 2NH3 (g)
(a) Calculate the mass of ammonia gas formed if 2
...
0 kg of hydrogen gas
...
: m (NH3) = 2
...
5 g
(a) Calculate the molarity of solution prepared by dissolving 175
...
0 L of brine solution
...
25 g ml1
...
3
...
5
...
0 L oxygen gas at STP
(b) 4
...
Calculate the number of moles :
(a) 05
...
75 M Na2CO3
(b) 7
...
2 g sucrose (C12H22O11)
7
...
07% hydrogen, 24
...
65% chlorine
...
96 g
...
8
...
5 - MARK QUESTIONS
1
...
3
...
(b) State Gay Lussac’s Law of gaseous volumes
...
1 M NaOH solution is required to neutralise
100 mL of concentrated aqueous sulphuric acid which contains 98%
H2SO4 by mass
...
H2SO4 is 1
...
NaOH reacts with H2SO4 according to the following equation :
2NaOH + H2SO4 Na2SO4 + 2H2O
(At
...
Calculate its average atomic mass
...
793 kg L1, what is its volume needed
for making 2
...
25 L of 0
...
How is it different from molarity ?
(b) Calculate the Molality of a solution of ethanol in water in which the
mole fraction of ethanol is 0
...
7
[XI – Chemistry]
UNIT-2
STRUCTURE OF ATOM
•
Atom is the smallest indivisible particle of the matter
...
Discovery
Nature of charge
Amount of charge
Mass
•
•
•
•
•
•
•
ELECTRON
Sir
...
J
...
6 1019 Coloumb
9
...
6 10
1
...
67492 1027 kg
Nucleus was discovered by Rutherford in 1911
...
Mass Number (A) : Sum of the number of protons and neutrons present in
the nucleus
...
0 108 m/s
v = frequency of s1 or Hz
= wavelength in metres
1
Wave number v is the reciprocal of wavelength v
...
A quantum of light is called photon
...
The line spectrum of hydrogen consists of Lyman Series (in UV region),
Balmer series (visible region), Paschen, Brackett and Pfund series (IR region)
...
Balmer series : n1 = 2, n2 = 3, 4, 5,
...
[XI – Chemistry]
8
•
Brackett series : n1 = 4 and n2 = 5, 6, 7,
...
The energy of electron in hydrogen atom is given by :
2 2 mZ2 e 4
En
n2h2
M = mass of electron, e = charge on electron, Z = atomic number of element
•
For hydrogen atom, energy of electron in nth orbit is :
–1
...
178 1018 Z2
–13
...
•
The lowest energy state of an electron in atom is called ground state (n = 1),
when an electron absorb energy, it jumps to higher energy level called excited state, (first excited state n = 2 for H)
...
e
...
18 × 10–18 2 2 J/atom such that n2 > n1
...
529Å n2
...
With this frequency, the kinetic energy of the photoelectrons ejected is zero
...
2
The minimum energy hv0 required for emission of photoelectrons is called
threshold energy or work function
...
However, number of photoelectrons ejected is proportional to the intensity
of incident radiation
...
e
...
The wave associated with a material particle is called de Broglie wave or
matter wave
...
It is given by
h
h
m p
where h is Planck’s constant and p is momentum of the particle
...
Heisenberg’s uncertainty Principle states that ‘‘It is impossible to measure simultaneously the position and momentum of a microscopic particle
with absolute accuracy
...
The product of their uncertainties is al
•
h
...
Quantum numbers
The four quantum numbers provide the following informations :
(1) Principal quantum number (n)
n = 1, 2, 3, 4,
...
(2) Azimuthal quantum number (l)
For a given value of n, it can have n values ranging from 0 to n 1
...
The number of orbitals
orbital angular momentum, i
...
, l l 1
2
in a subshell = 2l + 1
...
It determines the orientation of orbital
...
Pauli’s Exclusion Principle : ‘‘No two electrons in an atom can have the
same set of four quantum numbers
...
Therefore
an orbital can have at the most two electrons if they have opposite spins
...
’’ e
...
, N : 1s2, 2s2, 2px1, 2py1, 2pz1
...
’’
1
...
2
...
Increasing order of energy :
1s < 2s < 2p < 3s < 3p < 4s < 3d < 4p < 5s < 4d < 5p < 6s
Exception of Aufbau principle : Extra stability is associated with the
exactly half-filled and fully-filled orbitals
...
have extra stability, i
...
, lower energy and therefore, more stable
...
2
...
4
...
6
...
Indicate the number of electrons, protons and neutrons in the element 238 U
...
e = 92, p = 92, n = 146]
Name the experiment used in determination of the charge of an electron
...
[Ans
...
[Given : me = 9
...
0
...
Mention some other physical
quantity, which has the same dimension
...
[Ans
...
[Hint : Neutron (n) will not show deflection since it is electrically neutral]
8
...
mv
Therefore ve will be higher as compared to vp
...
An anion A3has 18 electrons
...
[Ans
...
What is the value of orbital angular momentum of 6s orbital ?
11
...
Name two physical quantities which can be estimated by principal quantum
number (n)
...
Which shell would be the first to have g-subshell ?
14
...
18]
15
...
16
...
[Atomic number of Cr = 24]
17
...
4
in +3 oxidation state
...
State Pauli’s exclusion principle
...
How many nodes are there in 3s orbital ?
[Ans
...
Why 1p, 2d and 3f subshells are not possible ?
21
...
State Hunds rule of maximum multiplicity
...
Using s, p, d notations, describe the orbital with the following quantum
numbers :
(a) n = 4, l = 2
(b) n = 1, l = 0
[Ans
...
Which quantum number determines the orientation of atomic orbital ?
25
...
Write the correct set of four quantum numbers for the valence electron (outermost electron) of potassium (Z = 19)
...
Which principle is not obeyed in writing of electronic configuration :
2s
2p
2- MARK QUESTIONS
1
...
[Ans
...
How will you detect the spot where
the rays strike ?
3
...
4
...
2 and the isotopes have the mass numbers 20 and 22
...
10%
5
...
(b) Can a thin foil of aluminium be used in place of gold (Au) in Ruther
ford experiment ? Give suitable explanation
...
]
6
...
7
...
Explain
...
A laser used to read compact disc (CD) emits red light of wavelength
700 nm
...
3
...
Electromagnetic radiation of wavelength 242 nm is just sufficient to ionise
the sodium atom
...
10
...
13
[XI – Chemistry]
11
...
Calculate the energy required for the process He+ (g) He2+ (g) + e
The ionisation energy for the H atom in the ground state is 2
...
[Ans
...
72 1018 J]
13
...
Write the possible values of l and ml ?
(b) List the quantum numbers (ml and l) of electrons for 3d orbital
...
Draw the boundary surface diagrams of d xy and d x2 y 2 orbitals
...
What is meant by degenerate orbitals ? Illustrate with the help of one example
...
How does a 1s orbital differ from a 2s orbital ? Mention two points in support
of your answer
...
Calculate the wave number for the shortest wavelength transition in the
Balmer series of atomic hydrogen
...
27419
...
Calculate (a) wave number and (b) frequency of yellow radiation having
wavelength 5800Å
...
724 104 cm –1
5
...
Calculate the energy associated with the first orbit of He+
...
[Ans
...
72 × 10–18 J, r = 0
...
Nitrogen laser produces a radiation at a wavelength of 337
...
If the
number of photons emitted is 5
...
[Ans
...
3 × 106]
21
...
Calculate the radius of
carbon atom if the length of this arrangements is 2
...
[Ans
...
06 nm]
22
...
If the statis electric charge on the oil drop is
–1
...
8]
[XI – Chemistry]
14
23
...
4%
more neutions than electron
...
What transition in the hydrogen spectrum would have the same wavelength
as the Balmer transition n = 4 to n = 2 of He+ spectrum
...
2
...
4
...
6
...
8
...
Differentiate between :
(a) Photon and quantum
(b) Orbit and orbital
(c) de Broglie waves and electromagnetic waves
(a) State Heisenberg uncertainty principle
...
’’ Justify the
statement on the basis of Heisenberg uncertainty principle
...
[1 eV = 1
...
3
...
86 1025 J
...
[Ans
...
76 109 s1]
Calculate the energy required to excite the electron in the atom from n = 1
to n = 2
...
312 106 J mol1
...
11 1031 kg)
...
18 1018)/n2 J
...
Calculate the longest wavelength of light in cm that can be used
to cause this transition
...
(a) Write the electronic configurations of the followings :
(i) H–
(ii) Na+
(iii) O2–
(b) Symbols
79
35 Br
and
79
Br can be written, whereas symbols
79
35 Br
and
35
Br are not acceptable
...
If
the ion contains 11
...
Assign the symbol
of this ion
...
(a) Define photoelectric effect ? Mention its one practical application in
daily life
...
Calculate threshold frequency (v0) and work function (W0) of the metal
...
4
...
91 1019 J]
2
...
Why it is not meaningful for a moving cricket
ball ?
(b) Which out of (i) electron (e), (ii) proton (p) (iii) particle, has maximum de Broglie’s wavelength ? [Assume that all are moving with the
same velocity
...
Calculate
the wavelength associated with particle B, if its momentum is half of A
...
1 107 m]
3
...
’’ ?
(b) Why is uncertainty principle not applicable to macroscopic and semimicro particles ?
(c) An electron has a speed of 40 ms-1 accurate upto 99
...
What is the
uncertainty in locating its position ? (me = 9
...
1
...
(a) State Aufbau principle
...
(ii) Chromium has configuration 3d 5 4s 1 and not 3d 4 4s 2
...
(a) The work function for caesium atom is 1
...
Calculate (i) the
threshold wave length and (ii) the threshold frequency of the
radiation
...
598 × 1014 S–1
(iii) 3
...
33 × 108 m S–1
(b) Among the following pairs of orbitals, which orbital will
experience the larger effective nuclear charge
(i)
2s and 3s
(ii)
3d and 3p
(i)
5
...
Therefore, the position of an
element in the periodic table depends on its atomic number
...
Types of Elements : s-, p-, d- and f- blocks :
s-block elements : Group 1 (alkali metals) and group 2 elements (alkaline
earth metals) which respectively have ns 1 and ns 2 outermost electronic
configurations
...
The outermost electronic configuration is ns2 np1-6
...
d-block elements (Transition elements) are the elements of group 3 to 12
having outer electronic configuration (n 1)d1-10 ns1-2
...
6d-series is incomplete
...
A cation is smaller but the anion is larger than the parent atom
...
Ionization enthalpy (iH) is the enthalpy change for the reaction : X(g)
X+(g) + e
Second ionization enthalpy (iH2) is more than the first ionization enthalpy
(iH1)
...
For the elements of second period, the correct order of increasing ionization enthalpy (iH) is :
iH1 : Li < B < Be < C < O < N < F < Ne ;
X(g) X(g)+ + e
For the elements of third period, the correct increasing order of ionization
enthalpy is :
iH1 : Na < Al < Mg < Si < S < P < Cl < Ar
For the group 1 elements, the ionization enthalpy decreases in the order :
[XI – Chemistry]
18
Li > Na > K > Rb > Cs
Ionization enthalpy and atomic radius are closely related properties depending upon the attraction of electrons towards the nucleus and repulsion of electrons from each other
...
eg H for N atom is zero
...
f-block Elements (Inner-transition Series)
Lanthanoides characterised by the filling of 4f orbitals, are the elements
following lanthanum from 58Ce to 71Lu
...
Characteristic outer electronic configuration is (n 2)f1-14 (n 1)d 0-1 ns2
...
Regular variation in physical and chemical properties are observed as we descend the group and move across a period from left to right in the periodic table
...
Exceptions : P, S, Cl have more negative egH than N, O, F respectively
...
Electronegativity (EN) : It is the qualitative measure of an atom in a
chemical compound to attract the shared electrons to itself
...
By giving a reference value of 2
...
Screening effect – Decrease in the force of attraction exerted by the nucleus
on the valency electrons due to the presence of electrons in the inner shells, is
called screening effect or shielding effect
...
19
[XI – Chemistry]
Anomalous Properties of Second Period Elements
Each element of second period, i
...
, first element of each of group 1 and 2
and groups 13-17 shows many properties which are not shown by its cogeners
...
Thus the first member of each group has only four valence orbitals (one 2s and
three 2p orbitals) for bonding, whereas the second member of the group has nine
valence orbitals (one 3s, three 3p and five 3d orbitals)
...
For example, B from [BF4]and Al, [AlF6]3
...
g
...
g
...
1 - MARK QUESTIONS
Name the scientist who gave birth to the periodic table
...
State the Modern Periodic Law
...
How many groups and periods are there in the long form of the periodic
table ?
5
...
6
...
Arrange B, C, N, O elements in increasing order of electron gain enthalpy
...
Write the electronic configuration of the element having atomic number 21
...
Explain the term electron gain enthalpy
...
Out of K and K+, which one would have larger size ?
11
...
Predict the position of the elements in the periodic table having the electronic
configuration :
(n 1)d1 ns2 for n = 4
1
...
[XI – Chemistry]
20
13
...
(b) having the highest electronegativity
...
The first (iH1) and the second (iH2) ionization enthalpies (kJ mol1) of
the three elements are given below :
I
II
III
iH1
403
549
1142
iH2
2640
1060
2080
15
...
17
...
19
...
21
...
Identify the element which is likely to be :
(a) a non-metal
...
[Ans
...
[Hint : Greater the nuclear charge, smaller is the size
...
Explain why ?
[Hint : Size of an anion is larger than the parent atom]
Write the general electronic configuration of f-block elements
...
Show by chemical reaction with water that K2O is a basic oxide
...
21
[XI – Chemistry]
2 - MARK QUESTIONS
1
...
(a) State Newland’s law of octaves
...
Name the groups of elements classified as s-, p-, d- and f-blocks in the
modern periodic table
...
How are Li and Mg related to each other in the periodic table ? Write the
name of another pair having such a relationship
...
(a) Name the first and last member of the 3d series
...
The ionization enthalpy per mole of atomic hydrogen is 1
...
Calculate the energy of the electron in the ground state of the hydrogen atom
...
313 106 J mol –1
2
...
023 10 mol
I
...
= E E1]
[Ans
...
18 1018 J]
[Hint : I
...
/atom =
6
...
It has four electrons
in the outermost shell
...
How many unpaired electrons are
present in an atom of that element ?
7
...
Why do the periodic properties such as ionization enthalpy, electron gain
enthalpy and electronegativity shows a decreasing trend down the group
but an increasing trend along a period ? Explain your answer
...
Identify the elements having the following description and write their electronic configuration also :
(a) Group 14, period 3
(b) Group 18, period 2
(c) Group 1, period 6
[Ans
...
On the basis of quantum numbers, justify that fifth period of the periodic
table should have eighteen elements
...
Lanthanoids and actinoids are placed in separate rows at the bottom of the
periodic table
...
[XI – Chemistry]
22
12
...
2px1
...
2px2 2py1 2pz1
Q = 1s2, 2s2
...
The element with atomic number 120 has not yet been discovered
...
14
...
Classify them as acidic or
basic oxide
...
Arrange the following species as stated, giving reasons :
(a) Increasing order of electronegativity (H, F, Cl)
(b) Increasing order of ionic size : N3, Na+, F, O2, Mg2+
16
...
17
...
18
...
19
...
20
...
(O) is less than that of Nitrogen (N)?
3 - MARK QUESTIONS
1
...
(b) Mention three main features of the modern periodic table
...
The diagram given below is a part of the periodic table
...
4
...
6
...
(a) (i) Name a transition metal
...
(b) How many atoms of element 35 can combine with an element having
atomic number 20 ? Write the formula of the compound
...
Among the elements X, Y and Z with atomic numbers 9, 12 and 36 respectively, identify an element which is :
(a) highly electropositive
(b) highly electronegative
(c) a noble gas
Give reason (s) for your choice
...
(b) Explain the following :
(i) LiF is less ionic than CsF
...
Justify the following statements :
(a) There are only fourteen lanthanoids and only fourteen actinoids
...
(c) 3d, 4d and 5d series consists of ten elements each
...
(a) Write the group numbers to which the elements belong to
...
(c) Write the formula of the compound formed between P and Q
...
(b) In group 13, Boron forms [BF4]whereas Aluminium forms [AlF6]3
...
Given below are the plots of first ionization enthalpy (iH) of elements of
the second period as a function of atomic number (Z) (Fig
...
2)
...
F
(1681)
O
C
(1314)
(1086)
B
(801)
2
4 6
8
Atomic number (Z)
550
500
Na (496)
450
Rb (403)
400
350
0
10
Li (520)
K (419)
10
Cs (374)
20 30 40 50 60
Atomic number (Z)
(a) First ionization enthalpy generally increases as we go across a period
and decreases as we descend a group
...
(c) Ionization enthalpy of nitrogen is more than that of oxygen
...
A, B, C are three elements with atomic number Z 1, Z and Z + 1 respectively
...
Answer the following questions :
(a) Predict the groups of A and C
...
The first (iH1) and the second (iH2) ionization enthalpies (in kJ/mol) and
the (egH) electron gain enthalpy (in kJ/mol) of a few elements are given
below :
Elements
IH1
IH2
egH
I
520
7300
60
II
419
3051
48
III
1681
3374
328
IV
1008
1846
295
V
2372
5251
+48
VI
738
1451
40
25
[XI – Chemistry]
Which of the above elements is likely to be :
(a) the least reactive element
...
(c) the most reactive non-metal
...
(e) the metal which can form a stable binary halide of the formula MX2
(X = halogen)
...
[XI – Chemistry]
26
UNIT-4
CHEMICAL BONDING AND MOLECULAR STRUCTURE
Atoms do form chemical bonds since their formation lead to the decrease in
the energy of the system
...
(b) Ionic bonds formed by the transference of electrons from the metallic
atom having low iH to the more electronegative and non-metallic
atom having more -ve egH resulting in the formation of a crystal having
high lattice enthalpy (LH)
...
The strength of hydrogen bond depends on the electronegativity difference
between H atom and the highly electronegative atoms like F, O and N having at
least one lone pair of electron
...
F > O H
...
N
Effects of hydrogen bonding : Intermolecular hydrogen bonding increases
m
...
, b
...
, solubility, viscosity and surface tension while intramolecular hydrogen
bonding has reverse effects
...
O
O
C O–
C
O–
and
O H
O CH3
(Chelation occurs)
(No Chelation)
All single bonds are sigma bond
...
(a) Bond energy increases from a single bond to trople bond
...
(c) Reactivity of a multiple bond is always more than a single band, due to
mobile nature of electrons
...
(2) Multiplicity of bonds : It decreases with the increase in the multiplicity
of bonds, for example bond length decreases in the order
C C C C C C
...
For example,
sp3 CH > sp2 C H > sp C H
Bond energy or bond dissociation enthalpy :Smaller the bond length,
the stronger will be the bond formed and larger will be bond dissociation enthalpy
...
The
dipole moment help to predict whether the molecule is polar or non-polar
...
For example,
dipole moment = 0 in case of CCl4 but 0 in case of CHCl3
...
Just as all covalent bonds have some partial ionic character, the ionic bond
also have partial covalent character
...
Geometrical shapes can be predicated with the help of Valence shell-Electron pair Repulsion (VSEPR) Theory
...
of electron pairs around the central atom in its Lewis structure
...
The
repulsive interaction between electron pairs decreases in the order IpIp > Ipbp
> bpbp
...
Type of
molecule
bp
Ip
CH4
4
0
4
Tetrahedral, HCH angle 109
...
5º
[XI – Chemistry]
Total no
...
The new orbitals that are formed are called hybridised or hybrid orbitals
...
of hybrid orbitals = No
...
Table 1
Arrangement of the electron pairs about a cental atom A
Type of
molecule
Total no
...
Shape of
Hybridisation type
Example
coordination entity
Linear
sp
[Ag(NH3)2]+
Tetrahedral
sp3
[Ni(CO)4], [NiCl4]2
Square planar
dsp2
[Ni(CN)4]2, [PtCl4]2
Trigonal bipyramidal
dsp3
[Fe(CO)5]
Octahedral
sp3d 2
[CrF6]3, [CoF6]3, [FeF6]3
d 2sp3
[Fe(CN)6]3, [Co(C2O4)3]3
29
[XI – Chemistry]
Molecular orbital theory was developed by F
...
S
...
This theory was able to explain the stability of the molecule, to calculate
bond order, to find out the nature of the bond formed (e
...
, single, double or
triple bonds), to calculate the bond length and predict the magnetic nature of the
species some of which was not explained by the valence bond theory
...
The increasing order of energies of various molecular orbitals (determined experimentally from spectroscopic data)
...
Define electrovalence of an element
...
Arrange the following molecules according to the increasing order of their
bond angles :
NH3, H2O, CH4
[Ans
...
He2 molecule does not exist
...
5
...
6
...
Give reason
...
Write the state of hybridisation of C in CO32ion
...
Which of the following species are paramagnetic ?
H2, H2+ and H2
9
...
10
...
Why ?
11
...
+
–
–
+
N N–O– < N=N=O
Which of the two structures has greater contribution to the resonance
hybrid
...
Arrange the repulsive interaction of electron pairs in the decreasing order
as per the VSEPR theory :
[Hint :lone pair-lone pair, lone pair-bond pair, bond pair-bond pair
...
Considering x-axis as the internuclear axis which out of the following will
form a sigma bond :
(a) 1s and 1s
(b) 1s and 2px
(c) 2py and 2py
(d) 1s and 2s
14
...
The HPH angle in PH3 is smaller than the HNH angle in NH3
...
What is percentage of s-character in sp and sp3 hybrid orbitals ?
17
...
18
...
what is the average bond enthalpy of H2O
...
Write the full form of (a) VSEPR, (b) LCAO
...
Which of the two bonds ionic or covalent is directional
...
Out of Mgo and NaCl, which has higher lattice energy?
2 - MARK QUESTIONS
1
...
State octet rule
...
3
...
Why is the shape of NH3 molecule pyramidal ?
5
...
How does it differ from electron gain enthalpy ?
6
...
Calculate the formal charges of the three atoms in O3 molecule
...
9
...
11
...
13
...
15
...
17
...
Write Lewis dot symbols for the following ions :
Li+, O2, Mg2+, N3
(Given Atomic no
...
Why does Li2 molecule not exist in nature (z = 3)
...
Define bond enthalpy
...
Write two points of difference between and -bond
...
90 1030 c
...
80 1030 c
...
Explain with their structures
...
Draw diagrams showing the formation of a double bond and a triple bond
between carbon atoms in C2H4 and C2H2 molecules
...
What is formal charge? Calculate the formal charge on each atom in the
: O – S O
...
Explain the concept of reasonance, write the two structures of ozone which
satisfy the octet rule ?
3 - MARK QUESTIONS
1
...
Define an electrovalent bond
...
Give two characteristics of an electrovalent compound
...
Three elements have the following Lewis symbols :
A
B
C
(a) Place the elements in the appropriate groups of the periodic table
...
(c) Write the formulae and the Lewis structures of the covalent compounds
formed between :
(i) A and B
(ii) A and C
4
...
(b) in which the central atom has an expanded octet
...
5
...
6
...
(b) CH3COOH
The internuclear separation in a KCl molecule in the vapour is 2
...
m
...
602 1019
Coulombs) from K to Cl atom
...
(b) Show the direction of the dipole moment
...
(Given : dipole moment of KCl is 3
...
(i) – 4
...
m
...
1
obs
3
...
1% ]
ionic
4
...
(i) 4
...
m
...
1%]
9
...
33
[XI – Chemistry]
10
...
Calculate the formal charge on each atom of NO2– ion
...
All the C–O bonds in carbonate ion (CO32–) are identical
...
2
...
4
...
6
...
Draw the structure of OF2 and mention the oxidation
states each of O and F
...
(b) Predict their magnetic behaviour
...
(a) Mention important conditions required for the linear combination of
atomic orbitals to form molecular orbitals
...
Write the necessary conditions for the formation
of hydrogen bond
...
Draw the molecular orbital diagram of O2 molecule
...
(b) Compare their relative stabilities
...
(a) Define the term hybridisation
...
(c) Describe the hybridisation in case of PCl5
...
Give reason for the following :
(i) H2S is a gas at ordinary temperature but H2O is liquid
(ii) Pure HCl liquid is a bad conductor of electricity while aqueous HCl is
a good conductor of electricity
...
Liquid HCl is a covalent compound
...
(iv) H2O is more polar than H2S
...
[Hint : BF3 has symmetrical triangular planar structure in
which net dipole moment is zero, where NF 3 has pyramidal
strcuture, where dipole moment is considerable
...
Intermolecular forces are the forces of attraction or repulsion between interacting particles (atoms and molecules)
...
Different types of van der Waals forces are :
(a) Dispersion forces or London forces
(b) Dipole-dipole forces
(c) Dipole-induce dipole forces
Boyle’s Law :
1
p
[constant pressure]
V
P1V1 = P2V2
[ constant pressure]
Charles’s law :
V1 V2
T1 T2
•
•
•
[constant pressure and n]
Gay Lussac’s Law :
P1 P2
[constant volume and n]
T1 T2
STP (Standard Temperature and Pressure)
STP means 273
...
e
...
Volume occupied by 1 mole gas at STP = 22
...
If pressure is taken as one atmosphere, then the standard molar volume is
22
...
Ideal gas equation
pV = nRT
R is universal gas constant
...
314 JK1mol1 = 0
...
083 L bar mol1 K1
[XI – Chemistry]
36
•
•
Combined gas law :
P1V1 P2 V2
T1
T2
Relationship between different types of Molecular speeds :
Most probable speed : average speed : Root mean square speed
...
414 : 1
...
732
1 : 1
...
224
Averge speed = 0
...
Most Probable speed = 0
...
•
Density and molar mass of a gaseous substance :
dRT
M
P
•
Dalton’s Law of partial pressure :
ptotal = p1 + p2 + p3 +
...
•
Compressibility factor : The extent of deviation of a real gas from an ideal
behaviour is expressed in terms of compressibility factor, Z, defined
PV
...
For real gases, greater
is the departure in the value of Z from 1, greater is the deviation from ideal
behaviour
...
This implies
that gas is more compressible then expected from ideal behaviour when Z > 1,
the gas is said to show positive deviation and the gas is less compressible than
expected from ideal behaviour
...
However at low temperatures, even these gases show negative
deviation i
...
, Z < 1
...
Boyle temperature : The temperature at which a real gas behaves like
an ideal gas over an appreciable pressure range is called Boyle temperature
or Boyle point
...
(b) The forces of attraction or repulsion between the gas molecules are
negligible
...
van der Waals equation :
a
P 2 V b RT
V
for 1 mol of the gas
an 2
P 2 V nb nRT for n moles of the gas
V
a and b are constants called van der Waals constants
...
As correction in
an 2
pressure is p 2 , therefore a = (p V2)/n2 = atm L2 mol2
...
The near constancy in the
value of b shows that the gas molecules are incompressible
...
Its unit is Nm–1
...
As a result, intermolecular forces decreases and hence
force acting per unit length decreases
...
du
f A
...
Effect of temperature on viscosity : viscosity decreases with increase in
temperature because with the increase in temperature the average kinetic energy
increases and the intermolecular forces can be easily overcome
...
What type of intermolecular forces operate in :
(a) noble gases
(b) Water
[XI – Chemistry]
38
2
...
3
...
4
...
How is pressure in atm related to the pressure in pascals ?
6
...
7
...
8
...
Mention the SI unit of universal gas constant (R)
...
Define aqueous tension
...
Why is it not possible to cool a gas to a temperature of absolute zero (0º K) ?
12
...
[Ans
...
Write the units of van der Waals constant a and b
...
Name the temperature at which real gases behave as ideal gases over appreciable range of pressure
...
Boyle temperature]
15
...
[Ans
...
Dalton’s law of partial pressures is not applicable to a gaseous mixture of
CO (g) and O2 (g)
...
Atmospheric pressure recorded in different cities are as follows :
Cities
Shimla
Bangalore
Delhi
Mumbai
p/N/m2
1
...
2 105
1
...
21 105
Consider the above data and identify the place at which liquid will
boil first
...
Shimla]
18
...
19
...
20
...
Arrange the following in the increasing order of
surface tension :
Water, alcohol and n-hexane
...
Differentiate between normal boiling point and standard boiling point
...
What property of moelcules of real gases in indicated by the van der Walls
constant a?
39
[XI – Chemistry]
2 - MARK QUESTIONS
Identify the states of matter in each case with following properties :
(a) Highly compressible
(b) Definite volume but indefinite shape
(c) Molecules move randomly within restricted space
(d) Intermolecular forces are strong
2
...
How is the law helpful in calculating the pressure of the gases which are collected over water ?
3
...
How is it represented mathematically ?
4
...
5
...
6
...
How is this law used in the metorological observations ?
7
...
Using the equation of state, pV = nRT, show that at a given temperature,
density of a gas is proportional to gas pressure (p)
...
Give correct reason for the following :
(a) Hot tea or coffee is sipped from a saucer
...
10
...
1° and –81
...
Which of these has stronger intermolecular forces and why?
11
...
1
...
Compressibility factor (Z) of a gas is given as Z
pV
...
(a) Z = 1, (b) Z > 1]
13
...
(a) The volume of gas is directly proportional to its absolute temperature
...
[XI – Chemistry]
40
14
...
0831 bar
dm3 mol–1 k–1)
...
Calculate the temperature at which the average speed of oxygen equals that
of Hydrogen at 20K
...
2
...
4
...
6
...
8
...
(b) Carbon dioxide is heavier than oxygen and nitrogen but it does not form
the lower layer of the atmosphere
...
With the help of gas laws, deduce an expression for the ideal gas equation
...
What will be the pressure of the gas mixture when 0
...
8 bar and
2
...
7 bar are introduced in a 1 L vessel at 27º C ?
Pressure of 10 g of an ideal gas ‘A’ at 27º C is found to be 2 bar
...
Find the relationship between their molecular
masses
...
MB = 4MA]
Calculate the total pressure in a mixture of 8
...
0 g of
hydrogen confined in a vessel of 1 dm3 at 27º C
...
083 bar dm3 K1 mol1
...
56
...
6 dioxygen and 167
...
If pressure of the mixture of gases in cylinder is 25 bar, what is the partial pressure
of dioxygen and neon in the mixture
...
5
...
75 bar]
Calculate the temperature at which the root mean square speed, average
–1
speed and the most probable speed of oxygen gas are all equal to 1500 ms
...
The remaining universe which can interact with the system constitutes the surroundings
...
A process that occurs infinitesimally slowly such that system always remains in equilibrium with its surroundings is called reversible process
...
e
...
The heat change at constant volume during the course of a reaction is measured by bomb calorimeter
...
e
...
H = qp = CpT
Heat change at constant pressure is measured in ordinary calorimeter
...
For a given change in state,
q and w vary depending how the change is carried out
...
Hence U is also a
state function
...
Work done during the expansion of gas against external pressure
Mechanical work or pressure volume work is given by W = Pex (V) =
Pex (Vf Vi) where Pex is external pressure acting on the system
...
If external pressure is not constant but changes during the process such
that it is always infinitesimally greater than the pressure of gas (pin)
...
The work done in a reversible process is given by
Vf
Vf
Wrev pin dv pdv 2
...
303 nRT log
Pi
Pf
where Pi = Initial pressure; Pf = Final pressure
In free expansion of an ideal gas in vaccum, no work is done by the gas
because no force is opposing expansion (pex = 0) in a reversible or irreversible
process
...
For isothermal irreversible change : U = 0
q = W = [pex (Vf Vi)]
For isothermal reversible change : U = 0
q W 2
...
ng = nP nR (gaseous phase)
Standard enthalpy of reaction (r H) is the enthalpy change for the
reaction when the reactants and products are in their standard states
...
Second law of thermodynamics : For a spontaneous change in a system,
the total entropy change Stotal is positive, i
...
, Ssys + Ssurr
...
Hence,
Stotal = 0 (at equilibrium)
...
Residual entropy : There are certain substance which possess certain entropy
even at absolute zero
...
Gibbs energy change (r G) and spontaneity : The following criteria can
be derived from second law of thermodynamics :
r G < 0
Spontaneous process
r G > 0
Non-spontaneous process
43
[XI – Chemistry]
r G = 0
At equilibrium
The reaction is called exoergonic if G < 0 and endoergonic if G >
0
...
The temperature
H
...
H is the enthalpy change of the reaction
...
The decrease
in the Gibbs energy is equal to the maximum possible useful work that can be
derived from a process
...
If a reaction is the sum of two or more constituent reactions, then
enthalpy of overall reaction is the sum of enthalpy changes of the constituent
reactions
...
(F o r d efin itio n o f cH, aH, mean bond
dissociation enthalpy (HA B),
lattice enthalpy (LH), fusH, vapH, subH please refer NCERT text book
Class XI, Part I, page 171 to 173
...
This means that
forward and reverse reaction should proceed with the decrease in Gibbs energy
which is possible if the free energy of the system in minimum at equilibrium,
i
...
, r G = 0
...
303 RT log K
and
rG= rHTrS
1- MARK QUESTIONS
1
...
3
...
5
...
7
...
9
...
11
...
13
...
15
...
17
...
19
...
Give an example of an open system
...
Specify the properties needed to describe the state of a thermodynamic system
...
Which of the following is not a state function :
(a) P
(b) T
(c) W
(d) U
Why U is a state function ?
Assign positive or negative sign to Wad when :
(a) work is done on the system
...
How does the state of thermodynamic system changes when electrical or
mechanical work is done on an adiabatic system ?
Heat is transferred from the surroundings to the close system, then what is
the change in internal energy ?
State first law of thermodynamics and write its mathematical equation
...
Define standard enthalpy of formation of a compound
...
Define a state function
...
4 kJ mol1
What is the standard enthalpy of formation of ammonia gas ?
[Ans
...
2 kJ/mol]
For an isolated system U = 0, what will be S ?
For the reaction : H2 (g) 2H (g)
What will be the sign of H and S ?
[Ans
...
22
...
24
...
26
...
0 kJmol1
2
2
[Hint : Since enthalpy of formation of NO is positive, it is thermodynamically unstable
...
Calculate its
calorific value
...
Predict the sign of Ssurr for an exothermic reaction
...
2 - MARK QUESTIONS
1
...
3
...
5
...
(b) Reversible work done on the gas in a cylinder which is compressed in
infinite number of steps and the volume changes from Vi to Vf
...
Differentiate between the following :
(a) Extensive and intensive properties
(b) Sublimation energy and enthalpy of atomisation
The following equations do not depict the enthalpy of formation
...
62 kJ mol1
(b) CaO (s) + CO2 (g) CaCO3 (s) Hr= 178
...
7
...
9
...
11
...
13
...
15
...
Standard enthalpy of formation of hydrazine [N 2 H 4 (l)], hydrogen
peroxide [H2O2 (l)] and water [H2O (l)] are 50
...
2 and 242
...
Calculate the standard enthalpy of formation for
the following reaction :
N2H4 (l) + 2H2O (l) N2 (g) + 4H2O (l)
In a process 701
...
What is the change in internal energy for the process ?
[Ans
...
0 g Al from 35º C to 55º C
...
[Ans
...
09 kJ]
Under what conditions the following reactions occur spontaneously :
(a) Both H and S are negative for the reaction
...
Calculate rHfor the reaction :
H2 (g) + Br2 (g) 2HBr (g)
Bond enthalpy of various bonds are HH = 436
...
0
kJ mol1 and HBr = 368
...
Hess’s law is a corollary of the first law of thermodynamics
...
Explain the following observations :
(a) When an ideal gas expands in vacuum there is neither absorption or
evolution of heat but when a real gas expands cooling is observed
...
(a) Decrease in enthalpy cannot be the sole criteria for spontaneity of a
reaction
...
(b) How can a chemical reaction with positive enthalpy and entropy changes
be made entropy driven spontaneous reaction ?
All spontaneous reactions follow the criteria Stotal = Ssys + Ssurr > 0
...
What will be the value of ?
G
1 mol1, T = 300 K
R = 8
...
0 mol of H2O (l) is
formed under standard conditions
...
0 KJ mol1,
T = 298 K
...
Predict the spontaneity of the following reaction on the basis of Stotal
...
4 JK1 mol1
[Ans
...
6 JK–1 mol–1
...
Give reason for the following :
(a) The enthalpy of neutralisation is always constant i
...
, 57
...
(b) The enthalpy of neutralisation is less than 57
...
19
...
0 kJ mol1
2
2
1
NO ( g ) O2 ( g ) NO 2 ( g )
f H 74 kJ mol1
2
[Hint : Heat of formation of NO (g) is 90
...
0 + (74
...
0 kJ mol1]
...
]
20
...
98
...
3 - MARK QUESTIONS
1
...
3
...
What type of wall does the system have ?
Calculate the lattice enthalpy of MgBr2, given that :
Enthalpy of formation of MgBr2 = 524 kJ mol1
[XI – Chemistry]
48
Sublimation enthalpy of Mg = 148 kJ mol1
Ionization enthalpy of Mg = 2187 kJ mol1
Vapourisation enthalpy of Br2 (l) = 31 kJ mol1
Dissociation enthalpy of Br2 (g) = 193 kJ mol1
4
...
6
...
(b) If enthalpy of vapourisation of water at 373 K = 40
...
[Ans
...
904 kJ/mol]
(c) A swimmer coming out from a pool is covered with a film of water
weighing about 18
...
How much heat must be supplied to evaporate
water at 298 k
...
The
enthalpy of vaporisation at 373 K is 44
...
vap U = 37
...
(b) Calculate bond enthalpy of HCl if bond enthalpy of HH bond is 436 kJ
mol1, ClCl B
...
is 242 kJ mol1 and heat of formation of HCl is
92
...
Calculate the standard enthalpy of formation of CH3OH (l) from the following data :
3
CH 3OH (l ) O 2 ( g ) CO 2 ( g ) 2H 2 O (l )
2
cH 393 kJ mol 1
C (graphite) O2 ( g ) CO 2 ( g )
1
H2 ( g) O2 (g ) H2 O (l )
2
7
...
r H 726 kJ mol1
f
H 286 kJ mol 1
Calculate the enthalpy change on freezing of 1
...
0º C to
ice at 10
...
[Ans
...
65 kJ/mol]
1 K1
Given :
Cp [H2O (l)] = 75
...
8 J mol1 K1
fus H = 6
...
During the combustion of 1 g graphite in bomb calorimeter, the temperature rised from 298 K to 299 K
...
7 kJ/K
...
qv = – 20
...
(a) Define lattice enthalpy
...
11
...
12
...
What are its applications ?
13
...
For the reaction :
2A(g) + B(g) 2C(g)
U = – 10
...
1 Jk–1
Calculate rG for the reaction and predict wheather the reaction may occur
spontaneously or not
...
0
...
Not spontaneous]
15
...
mol–1 and 330 kj
mol–1 respectively
...
H and S for the reaction
1
O2 g
2
are 30
...
Calculate the temperature
at which the Gibb’s energy charge for the reaction will be zero
...
(a) State Hess’s law of constant heat summation
...
You are
given following data :
H
r
(i)
C (graphite) O2 (g ) CO 2 ( g )
1
(ii) H 2 ( g ) O2 ( g ) H2 O (l )
2
(iii) CO2 ( g) 2H2 O (l ) CH ( ) 2O
4 g
2
2
...
51kJ mol 1
Hr 285
...
3 kJ mol
1
[Ans
...
2 kJ mol1
S[N2 (g)] = 191
...
6 JK1 mol1
S[NH3 (g)] = 192
...
314 JK1 mol1
(b) Calculate the value of Kp for the above reaction at 300 K ?
3
...
What is the effect of temperature on entropy change ?
(b) Calculate the entropy change in surroundings when 1
...
Melting point of ice is 273 K
...
(a) A reaction is found to be endothermic and S is +ve
...
0 kJ mol1
...
5 kJ mol1 and 285
...
51
[XI – Chemistry]
5
...
Heat (q) and work done (W) are not
state functions but their sum is a state function
...
7
...
H
|
H–C–H (g) + 2O =O O = C = O (g) + 2H – O – H (g)
|
H
Given Bond
Bond Enthalpy (kJ mol–1)
C=O
741
C–H
414
O–H
464
O=O
489
Predict the sign of S for the following changes :
(a) 2Cl (g) Cl2 (g)
(b) 2A (g) + B (g) 2C (g)
(c) 2CaCO3 (s) 2CaO (s) + 2CO2 (g)
(d) Freezing of water
(e) Temperature of alum crystal is changed from 273 K to 298 K
...
(b) Two litres of an ideal gas expands isothermally against an external
pressure of 1 atm until its final volume becomes 10 L at STP
...
(ii) Calculate the work done by the gas if it expands reversibly
...
(b) Predict the direction in which a reversible reaction will move when
G < o
...
09 105 J mol1,
fG[C6H6 (g)] = 1
...
314 JK1 mol1
...
The criterion for equilibrium for
the reaction aA bB cC dD is rG = 0
...
e
...
rG can
never be zero because it is calculated from therG of the reactants and products
...
303 RT log K
and rG = rH TrS = 2
...
)
where Kp = Kc (RT)ng
ng = [sum of stoichiometric coefficients of gaseous products
sum of stoichiometric coefficients of gaseous reactants]
Predicting the direction of reaction : The direction of reaction can be
predicted by the value of reaction quotient Qc which is defined the same way as
equilibrium constant Kc except that the concentrations in Qc are not necessary
equilibrium values
...
If Qc = Kc, no net
reaction occurs
...
Chemical equation
Equilibrium constant
Kc
aA bB cC dD
K
1
K
K2 = Kn
cC dD aA bB
K1
naA nbB ncC nd D
a
b
c
d
A B C D
n
n
m
n
K3 = K1/n
53
[XI – Chemistry]
When individual balanced equations are combined, multiply their
equilibrium constants to obtain the equilibrium constant for the net reaction
...
Le Chatelier’s principle can be used to study
the effect of various factors such as temperature, concentration, pressure, catalyst
and inert gases on the direction of equilibrium and to control the yield of products
by controlling these factors
...
The pH scale :
Activity of hydrogen (aH+) = [H+]/mol L1
pH = log aH+ = log {[H+]/mol L1}
pOH = log {[OH]/mol L1}
and
pH + pOH = 14
H + OH 1
...
e
...
Poly protic acid solution contain a mixture of acids like H2X, HX
and X2 in case, of diprotic acids like H2S, H2CO3 and oxalic acid
...
Hydrolysis of salts and pH of their solutions : Hydrolysis of salt is defined
as the reaction of cation or anion with water as a result of which the pH of water
changes
...
Salts of strong acids and strong bases (e
...
, NaCl) do not hydrolyse
...
2
...
g
...
(The anion acts as a base)
...
Salt of strong acids and weak bases (e
...
, NH4Cl) hydrolyse, pH < 7
...
55
[XI – Chemistry]
M H 2 O MOH H +
1
pK b log c
2
Salt of weak acids and weak base (e
...
, CH3COONH4) hydrolyse
...
pH 7
4
...
Basic buffer : Solution of weak base and its salt with strong acid e
...
,
NH4OH + NH4Cl
Acidic buffer : Solution of weak acid and its salt with strong base, e
...
,
CH3COOH + NaOH
...
In the absence of equilibrium,
i
...
, if the concentration of one or more species is not the equilibrium
concentration, the product of concentration of ions raised to powers equal to
respective stoichiometric coefficients appearing in balanced chemical equation
is called Qsp, the ionic product of salt
...
1- MARK QUESTIONS
1
...
4
...
6
...
8
...
Give an example also
...
’
At what temperature the solid and liquid phase of the same substance are in
equilibrium with each other ?
State the law of chemical equilibrium
...
Mention the effect of temperature on solubility of a gas in liquid
...
Write the expression of Kc for the following reaction :
9
...
Cu NO3 2 (s) 2CuO (s ) 4NO2 (g ) O2 (g )
10
...
3 10 at 1000 K :
NO (g ) O3 (g ) NO2 (g ) O2 (g )
Find the value of Kc for the following :
1
1
1
1
NO (g ) O3 (g ) NO2 (g ) O2 ( g )
2
2
2
2
11
...
061
...
12
...
13
...
14
...
15
...
Define solubility product
...
What is meant by ionic product of water ?
57
[XI – Chemistry]
18
...
20
...
22
...
24
...
26
...
Calculate the pH of 0
...
Why does BF3 act as a Lewis acid ?
Write the conjugate acid of NH3
...
Define common ion effect
...
Predict the direction of reaction when Qc > Kc
...
Explain
...
Write the condition when is neglected in comparison to C
...
Arrange the following acids in increasing order of their pKa values :
HCl, HBr, HF and HI
...
Write the unit of Kp for the following equilibrium :
N 2 O 4 (g ) 2NO 2 (g )
30
...
31
...
8 104, what is the Kb value of its
conjugate base at 298 K
...
0 1014 at 298 K
...
Kb (F–) = 1
...
Explain why pure NaCl precipitates out when HCl gas is passed in brine
solution
...
2
...
(a) Write an expression of Kp for the following reaction :
CaCO3 (s ) CaO (s ) CO 2 (g )
(b) Mention the effect of decreasing the concentration of CO2 on direction
of reaction
...
(b) Give one example each of an acidic buffer and a basic buffer
...
5
...
7
...
9
...
11
...
13
...
15
...
(a) Vapour pressure of water, acetone and ethanol at 293 K are 2
...
36
and 5
...
Which of these have the lowest and highest
boiling point ?
(b) At 293 K, which of these will evaporate least in a sealed container
before equilibrium is reached ?
The concentration of hydrogen ion in soft drink is 3
...
Calculate its pH
...
Assign reasons for the following :
(a) A solution of NH4Cl in water shows pH less than 7
...
(a) Mention the difference between a weak electrolyte and a strong
electrolyte
...
0 108 M solution of HCl
...
pH = 6
...
(b) The pKa of acetic acid and pKb of ammonium hydroxide are 4
...
75 respectively
...
[Ans
...
005]
(a) Write the conjugate acid and conjugate base of H2O
...
If 0
...
(Molar mass of KOH = 56 g mol1)
[Ans
...
70]
The value of Kc for the reaction :
3O 2 ( g ) 2O3 ( g )
59
[XI – Chemistry]
16
...
18
...
20
...
0 105 at 25º C
...
6 102 M, calculate the concentration of O3
...
1 106)
[Ans
...
46 L of water]
The pH of 0
...
50
...
The cations of strong bases like Na+, K+, Ca2+, Ba2+ etc
...
get hydrated in water but do not
hydrolyse
...
2 mole of NH4Cl and 0
...
Kb for NH4OH = 1
...
How much CH3 COONa should be added to 1 litre of 0
...
0 ? Ka = 1
...
3 - MARK QUESTIONS
1
...
02M CaCl2 and 0
...
Will
a precipitate form ? Given : Ksp for CaSO4 = 2
...
2
...
(ii)
H2S is passed in acidic medium to precipitate group 2 cations
...
3
...
(b) For the reaction :
2NOCl 2NO ( g ) Cl2 ( g )
The value of Kc = 3
...
Calculate Kp at this temperature
...
kp = 3
...
(a) Define reaction quotient
...
0 × 10-3
mol L–1 and 2
...
Predict whether at this stage the concentration of NH3 will increase or
[XI – Chemistry]
60
decrease
...
6
...
N 2 (g ) 3H 2 (g ) 3NH3 (g ) at 500 K
...
(b) pressure is decreased
...
(a) Give one example each of a Lewis and a Lewis base
...
Explain
...
8 × 10–5, 4
...
respectively
...
Ammonia is prepared by Haber’s process in which the following
reaction occurs :
N 2 3H 2 2NH3 93
...
of ammonia :
(a) Increasing pressure
(b) Increasing temperature
(c) Use of a catalyst at an optimum temperature
9
...
3 g of Ca(OH)2 dissolved in water to give 500 mL of solution
...
0 mL of 13
...
0L solution
...
1M H 2SO4 + 10 mL of 0
...
[Ans
...
21; (ii) 1
...
00]
10
...
8
...
5 mol L1 of HI (g) is present at equilibrium at 700 K, calculate
the concentrations of H2 (g) and I2 (g) assuming that we initially started
with HI (g) and allowed it to reach an equilibrium at 700 K
...
[H2] = [I2] = 0
...
One mole of H2O and one mole of CO are taken in a vessel and heated to
725 K
...
[Ans
...
44]
12
...
265 atm at 1050 K
(a) If the initial partial pressure are pCO = 1
...
80 atm,
predict the direction of rector
...
The reaction moves backwards]
(b) Calculate the equilibrium partial pressure of CO and CO2 at 1050 K
...
[PCO] = 1
...
[PCO2] = 0
...
]
13
...
002 M solutions of sodium iodate and cupric chlorate
are mixed together
...
4 108
...
Ionic product = 1 × 10–9, No precipitation]
14
...
1M solution of an acid (HA) is 2
...
Calculate the ionisation
constant of the acid and its degree of ionization in solution
...
Ka = 2
...
57%]
15
...
23 g/L of solution
...
[Molar mass of Sr(OH)2 = 121
...
[Ans
...
1581 M ; pH = 3
...
3162 M
[XI – Chemistry]
62
5 - MARK QUESTIONS
1
...
Explain
...
Write the
conjugate acid and conjugate base formed by them :
H2O and HSO4–
(c) At 450 K, Kp = 2
...
[Ans
...
47 × 1011 M–1]
2
...
Give appropriate reasons
...
10M ammonia solution
...
0 ml of this solution is treated with 25
...
10M HCl
...
77 × 10–5
...
11
...
24]
3
...
(ii) At 293 K, if one starts with 1
...
18 mol of
ethanol, there is 0
...
Calculate the equilibrium constant
...
Kc = 22
...
5 mol of ethanol and 1
...
214 mol of ethylacetate is found after sometime
...
Qc < Kc, therefore equilibrium is not reached]
4
...
(c) Using a catalyst ?
(a) Arrange the following in the increasing order of Ka :
HF, H2O, NH3, CH4
(b) The Kb value for dimethylamine, (CH3)NH, is 5
...
Calculate its
degree of ionization in its 0
...
[Ans
...
162]
(c) Calculate the percentage of dimethylamine ionized if the solution is
also 0
...
[Ans
...
0054]
[XI – Chemistry]
64
UNIT-8
REDOX REACTIONS
Oxidation and Reduction :
Oxidation is a process which involves either of the following :
(a) addition of oxygen and removal of hydrogen
...
(c) increase in the oxidation state of an electropositive element
...
reduction is the reverse process of oxidation
...
N
...
g
...
(b) F has oxidation number –1
...
In O22– ox
...
is –1, in O2– is
–½, in OF2 is +2, O2F2 is +1
...
(e) The oxidation number of group I elements is +1 and group 2 is +2
...
Note : In an organic compound containing C, H, O
...
65
[XI – Chemistry]
Cu2O (Cuprous oxide)
Oxidation state of Copper = +1
Stock notation of Cu2O will be Cu2(I)O
...
(a) It connects the solution of two half-cells
...
1 - MARK QUESTIONS
1
...
3
...
5
...
Define the term oxidation and reduction in terms of oxidation number
...
Which one of the following is a case of reduction :
(a) Sn4+ Sn2+
(b) Sn2+ Sn4+
(c) Fe2+ Fe3+
(d) Cl Cl0
[XI – Chemistry]
66
6
...
(b) 3 to 2
(d) +3 to +2
The reaction :
3ClO (aq) ClO3 (aq) + 2Cl (aq)
is an example of :
(a) Oxidation
(b) Reduction
(c) Disproportionation
(d) Decomposition
8
...
9
...
10
...
Suggest
half reactions in this process
...
Justify that the reaction :
2Cu2O (s) + Cu2S (s) 6Cu (s) + SO2 (g)
is a redox reaction, identify the species oxidised/reduced
...
Construct the cell in which the given reactions are taking place, which
electrode shall act as anode (negative electrode) and which one as cathode
(positive electrode) :
(a) ZnSO4 + CuSO4 = ZnSO4 + Cu
(b) Cu + 2AgNO3 = Cu(NO3)2 + 2Ag
3
...
80, 0
...
12 and 0
...
Arrange them in decreasing
order of their electropositive character
...
]
67
[XI – Chemistry]
4
...
6
...
Given the standard electrode potential :
K+/K = 293 V
:
Ag+/Ag = 0
...
79 V :
Mg2+/Mg = 2
...
74 V
Arrange these in increasing reducing power
...
Write a practical application of redox couple
...
87V; ECl2/Cl– = +1
...
09V; EI2/I– = 0
...
3 - MARK QUESTIONS
1
...
...
(c) Solution of AgNO3 turns blue when copper rod is immersed in it
...
Account for the following :
(a) HNO3 acts only as an oxidising agent while HNO2 can act both as
reducing and oxidising agent
...
(c) Ozone acts as an oxidising agent
...
In HNO2 oxidation number of
nitrogen is +3, it can decrease or increase with range of –3 to +5, hence
it can act as both oxidising and reducing agent
...
]
3
...
4
...
Write one example of each type of redox reactions :
(a) Combination reaction
(b) Decomposition reaction
(c) Metal displacement reaction
6
...
Identify the species undergoing oxidation and reduction :
(a) H2S (g) + Cl2 (g) 2HCl (g) + S (s)
(b) 3Fe3O4 (s) + 8Al (s) 9Fe (s) + 4Al2O3 (s)
(c) 2Na (s) + H2 (g) 2NaH (s)
8
...
(b) When conc
...
(c) AgF2 is unstable compound and a strong oxidising agent
...
The oxidation number can decrease or increase,
because of this H2O2 can act both oxidising and reducing agent
...
When NaBr is heated HBr is produced,
which is a strong reducing agent and itself oxidised to red vapour of
Br2
...
5s0
Ag2+ 4d 9
...
9
...
Balance the following redox reaction by ion electron method (in basic
medion) :
(i) MnO4– + I– MnO2 + IO3–
(ii) Cl2 + OH– Cl– + ClO3–
...
Hydrogen (1s1) can gain one electron to form H ion like halogens
...
It resembles both alkali
metals and halogens but also it differs from both as well, therefore it is placed
separately
...
33 years)
Hydrides :
(1) Ionic hydrides are formed with most of s-block elements
...
Infact BeH2 and MgH2 are
polymeric in nature
...
They are further classified as :
(a) Electron deficient hydrides are formed by group 13 elements e
...
, B2H6
...
(b) Electron precise hydrides are formed by group 14 elements, e
...
, CH4
...
Elements of group 15-17 form this type of hydrides
...
Presence of lone pair(s) on highly electronegative
atoms like N, O and F in hydrides results in intermolecular hydrogen bond
formation leading to the association of molecules resulting in exceptionally high
m
...
and b
...
(3) Metallic or non-stoichiometric or interstitial hydrides are formed by
d- and f-block elements
...
87, TiH1
...
8, ZrH1
...
75 etc
...
(435
...
It shows
reactions by :
(a) loss of the only electron to give H+
...
(c) Sharing electrons to form a single covalent bond
...
The strength of H2O2 solution is expressed as volume strength as given
below :
Molarity 11
...
6 = Volume strength of H2O2
1 - MARK QUESTION
1
...
2
...
3
...
[XI – Chemistry]
72
4
...
How many hydrogen-bonded water molecule(s) are present in CuSO4
...
Give an example of ‘non-stoichiometeric hydrides’
...
Why is hydrogen regarded as fuel for future ?
8
...
9
...
Name the compound which is manufactured by repeated electrolytic
enrichment of water
...
Hydrogen gas is relatively inert at room temperature
...
Which property of water makes it a unique subvstance on earth?
13 Which groups in d-block elements do not form metallic hydrides
...
Write two chemical reactions to show the atmospheric nature of water
...
Complete the following reactions :
(a) NaH (s) + H2O
(b) LiH + Al2Cl3
3
...
4
...
8H2O) ?
5
...
Explain why hard water does not produce lather with soap ?
7
...
(b) Water is quite stable and does not dissociate in to its elements even at
high temperature
...
(b) Due to its high negative enthalpy of formation (fH = 285
...
Write ionic equations for each of the following reactions :
(a) H2O2 reduces acidified potassium permanganate solution to colourless
manganese sulphate
...
9
...
10
...
3 - MARK QUESTIONS
1
...
3
...
Define the following with one example of each :
(a) electron-deficient hydride
(b) electron-precise hydride
(c) electron-rich hydride
Account for the following :
(a) PCl5 exists but PH5 does not
(b) Water is responsible for moderation of the climate and the body
temperature of living beings
(c) Hard water is not suitable for boilers as well as for laundary
...
(b) High heat of vapourisation and high heat capacity
...
]
Complete the following reactions :
(a) Ca3H2 + H2O
(b) AlCl3 (g) + H2O
(c) CaO (s) + H2O
Write chemical emulation involved in the preparation of hydrogen peroxide
from
(a) Barium peroxide
(b) Peroxide sulphate
(c) 2-Ethyl anthraquinol
[XI – Chemistry]
74
5
...
What is permutit method for the removal of permanent hardness of water ?
Give the name and chemical formula of the inorganic salt and the reaction
involved in this method
...
Assign the reason for the following observations :
(a) The temporary hardness of water is removed by boiling
...
(c) Regeneration of sodium zeolite is essential by brine
...
Complete the following reactions :
(a) CO (g ) + H 2 (g )
catalyst
heat
(b) Zn + NaOH
(c) P4O10 (s) + 6H2O
9
...
(b) Dihydrogen is reduced by Na to form NaH, i
...
, Na+H–
...
]
10
...
(c) NaH has higher reducing character than H2O
...
Classify the following reactions as hydrolysis, redix and hydration reaction
...
What are the main limitations of dihydrogen to be used as a fuel?
13
...
Due to the low ionization enthalpy, the electrons of alkali metals can be
easily excited to the higher energy levels by the small energy provided by the
Bunsen flame
...
Photoelectric effect : Due to low ionization enthalpies, alkali metals
especially K and Cs show photoelectric effect
...
Their reducing character in aq
...
The degree of hydration, however,
decreases with the increase in ionic size as we move from Li+ to Cs+
...
g
...
Since the mobility of
ions is inversely proportional to the size of their hydrated ions, therefore, amongst
the alkali metal ions, lithium has the lowest ionic mobility aqueous medium
...
2M + 2H2O 2MOH + H2
Reaction with oxygen : All the alkali metals when heated with oxygen
form different types of oxides
...
In all
these oxides, the oxidation state of the alkali metals is +1:) Superoxides are
coloured and paramagnetic as these possess three electron bond (:O
_·_·_·_O:)where
one unpaired electron is present
...
77
[XI – Chemistry]
M2O + 2H2O 2M+ + 2OH– + H2
2M2O2 + H2O 2M+ + 2OH
2MO2 + 2H2O 2M+ + 2OH + H2O2 + O2
Reaction with hydrogen : All the alkali metals when heated with hydrogen
form ionic crystalline hydrides of the general formula M+H
...
2M X 2 2M X
With the exception of LiF, all other lithium halides are covalent
...
Reaction with nitrogen : Only lithium reacts with nitrogen to form lithium
nitride (Li3N)
...
The solutions on standing liberate
hydrogen resulting in the formation of an amide
...
red heat
Li 2 CO3 Li 2 O CO 2
Nature of nitrates : LiNO3 on heating decomposes to give NO2 and O2
while the nitrates of the other alkali metals decompose on heating to form nitrites
and O2
...
Diagonal relationship
Lithium shows diagonal relationship with magnesium (i) Similar atomic
and ionic raddi (ii) Similar polarizing power
r(Li+) = r(Mg2+)
Alkaline Earth Metals
Flame colouration : Like alkali metal salts, alkaline earth metal salts also
impart characteristic flame colouration
...
Consequently, the colour imparted to the flame shows a
gradual shift from red to violet
...
Chemical properties of alkaline earth metals
(1) Reaction with water
...
M + 2H2O 2M(OH)2 + H2
where M = Mg, Ca, Sr or Ba
(2) Reaction with oxygen
...
2M O 2 2MO
(M = Be, Mg or Ca)
M O 2 MO 2
(M = Be, Sr or Ra)
Metal oxide
Metal peroxide
(3) Reaction with hydrogen
...
BeH2 can be prepared by the reaction of
2BeCl2 + LiAlH4 2BeH2 + LiCl + AlCl3
(4) Solubility in liquid ammonia
...
These solutions decompose very slowly forming
amides and evolving MH2
...
When heated with N2, alkaline earth metals
79
[XI – Chemistry]
form their respective nitrides (M3N2)
...
g
...
When heated with halogens (F2, Cl2, Br2 or
I2), all the alkaline earth metals form halides of the general formula (MX2)
...
Beryllium halides are essentially covalent and soluble in organic
solvent
...
Oxides and Hydroxides :
The enthalpies of the formation of the oxides are quite high, So they are
very stable to heat
...
Carbonates : The solubility of the carbonates in water decreases as the
atomic number of the metal in increases
...
But the thermal stabilities of
the carbonates increases in the order BeCO3 < MgCO3 < CaCO3 < SrCO3 <
BaCO3 and these decompose on heating forming metal oxide and carbon
dioxide
...
Sulphate : The solubilities of the sulphates of alkaline earth metals decreases
as we move down the group from Be to Ba
...
4
...
2M (MO3)2 2MO + 4NO2 + O2
ONE MARK QUESTIONS
1
...
Write general electronic configuration of alkali and alkaline earth metals ?
Among the alkali metals, which element has :
[XI – Chemistry]
80
(a) Strongest reducing character in aqueous medium
...
3
...
Why alkali metals are highly reactive ?
5
...
State one use of liquid sodium metal
...
LiCl is soluble in organic solvent
...
]
8
...
9
...
10
...
Li2CO3 has lower thermal stability than that of Na2CO3, why ?
12
...
Lithium is a less reactive alkali-metal yet it is the best reducing agent! why?
14
...
2- MARK QUESTION
1
...
2
...
3
...
Why ?
4
...
5
...
(b) Lithium shows similarities to magnesium and similarly beryllium to
aluminium in many of their properties, name this relationship and give
its cause
...
Explain why alkali metals are never found in free state ?
81
[XI – Chemistry]
7
...
Why ? What happens to the magnetic
nature of the solution when the concentrated solution of NH3 is added to the
blue coloured solution ?
8
...
Explain the reason
...
This excited state is quite unstable and therefore
when these excited electrons come back to its original level, they emit extra
energy which fall in the visible region
...
What happens when –
(a) Potassium metal burns vigorously in oxygen
...
11
...
(b) Be and Mg are not detected by flame
...
Arrange the following accordingly –
(a) NaI, NaF, NaCl, NaBr (increasing order of melting point)
...
3 - MARK QUESTIONS
1
...
Assign the appropriate reason for the following :
(a) Solubility of alkaline earth metal hydroxides increases down the group
...
(c) Lithium salts are commonly hydrated
...
4
...
6
...
8
...
(a) Ammonium chloride and calcium hydroxide
...
(c) Calcium chloride and sodium carbonate
...
State as to why :
(a) KO2 is paramagnetic
...
(c) Sodium peroxide is widely used as an oxidising agent
...
(b) Carbonate part of Na2CO3 get hydrolysed by water to form an alkaline
solution
...
(b) Chlorine reacts with slaked lime
...
Sodium hydroxide is generally prepared by the electrolysis of brine solution
in the Castner-Kellner cell :
(a) Write the reactions that occur in the cell
...
Complete the following reactions :
(a) NaCl + NH3 + H2O + CO2
...
+ CO
(c) Na2CO3 + SiO2
...
Write balanced chemical equation of hydrolysis of sodium oxide, sodium
peroxide, sodium superoxide
...
Comment on the following :
(a) Lituim is the only alkali metal to form nitride directly
...
12
...
(i) Na (ii) K (iii) Rb
(iv) Cs
...
(i) Li (ii) Na (iii) K (iv) Cs
...
...
(c) Li metal is kept wrapped in paraffin wax and not stored in kerosene
...
(e) LiCl is more covalent than NaCl
...
Thus KF will undergo above nucleophilic substitution
...
[XI – Chemistry]
84
(c) Due to small size and high nuclear charge alkaline earth metal ions
have higher tendency of hydration
...
Explain the following observations :
(a) Lil is more soluble than KI in ethanol
(b) BeO is almost insoluble but BeSO4 is soluble in water
(c) Sodium reacts with water less vigorously than potassium
(d) Halides of alkaline earth metals form halide hydrates such as
MgCl2, 8H2O, CaCl2, 6H2O
SrCl2, 6H2O and BaCl2
...
[Hints :
(a) High polarising capabvility of Li+ ion
(b) Greater hydration enthalpy of Be 2+ in BeSO4 overcome the lattice
enthalpy
(c) Increase in the electropositive character down the group
...
(e) Hydration enthalpy decreases down the group
...
It arises due to poor or ineffective shielding of the
ns2 electrons of the valence shell by the intervening d- and/or f-electrons
...
In group 13 elements, inert pair effect
is more pronounced in Tl
...
Further due to inert
pair effect, as we move down the group, the stability of +3 oxidation state
decreases while that of +1 oxidation state increases
...
25 V
The decrease in stability of +3 oxidation state with increasing atomic number
is due to decrease in bond energy with increase in size from Al to Tl
...
Stability of +1 oxidation state follows the trend : Ga < In < Tl
•
Halides : All the elements of group 13 (except thallium which preferably
forms thallous monohalides) form trihalides of the general formula MX3
where X = F, Cl, Br and I
...
e
...
e
...
Whereas boron trihalides exist as only monomers, aluminium
trihalides exist as dimers
...
Consequently
trihalides of group 13 elements behave as Lewis acids
...
However,
as we move down the group from C to Pb, the stability of +4 oxidation state
decrease while that of +2 oxidation state increases due to inert pair effect
...
The stability of the divalent state
increases in the sequence Ge < Sn < Pb
...
The tendency of an element to form chains depends
upon the strength of the element-element bond
...
As we move down the group, the
element-element bond strength decreases very rapidly, i
...
,
Element-Element
C C Si Si
Ge Ge
Sn Sn
Bond strength (kJ mol1)
348
260
240
297
Therefore, the tendency for catenation decreases in the order C > > > Si >
Ge Sn > > Pb
...
p-p and p-d multiple bonding : Amongst group 14 elements, carbon
shows a pronounced ability to form p-p multiple bonds with itself (e
...
, in
graphite) and with other elements especially nitrogen and oxygen
...
This
is the reason that silicon exists only in the diamond structure
...
Thus trimethylamine, N(CH3)3 is pyramidal (N is
sp3-hybridized) and is more basic whereas similar silicon compound trisilylamine,
N(SiH3)3 is planar (N is sp2-hybridized) and is less basic
...
•
Chemical Properties
Nature of bonding : The compounds of group 14 elements which show an
oxidation state of +4 are covalent while those which show an oxidation of +2 are
ionic in nature
...
87
[XI – Chemistry]
Formation of halides :
(i) Tetrahalides : All the elements of group 14 form tetrahalides of the
general formula, MX4 where X = F, Cl, Br or I
...
The stability of these tetrahalides
decreases as we move from C to Pb, i
...
,
CCl4 > SiCl4 > GeCl4 > SnCl4 > PbCl4
Or
CX4 > SiX4 > GeX4 > SnX4 > PbX4
(ii) Dihalides : All the elements of group 14 form dihalides of the formula,
MX2 where X = F, Cl, Br or I
...
Thus, the dihalides of tin and Pb, i
...
, SnCl2
and PbCl2 are quite stable
...
g
...
•
Formation of oxides : All the elements of this group form two types of
oxides : (i) monoxides and (ii) dioxide
...
e
...
These oxides except SiO and
GeO are quite stable
...
(ii) Dioxides : All these elements form dioxides of the general formula,
MO2 i
...
, CO2, SiO2, GeO2, SnO2 and PbO2
...
CO2
is a monomeric, linear molecule and hence exists as a gas while the dioxides of
all other elements are crystalline solids with high melting points due to the
formation of three dimentional network of bond
...
Since the empirical formula
R2SiO (where R = CH3 or C6H5 group) is similar to that of a ketone (R2CO), the
name silicones have been given to these materials
...
Silicones are water repellent, heat resistant, chemically inert, resistant to
oxidation and attack by organic acids and good electrical insulators
...
, as lubricants at high and low temperatures, as antifoaming agents, as sealants
...
[XI – Chemistry]
88
1 - MARK QUESTIONS
1
...
2
...
3
...
4
...
5
...
6
...
Diamond is covalent, yet it has high melting point
...
White fumes appear around the bottle of anhydrous aluminium chloride
...
9
...
Atomic radius of gallium (135 pm) is less than that of aluminium (143 pm)
...
Boron cannot form B3+ ions
...
The +1 oxidation state gets progressively stabilized from Ga to Tl
...
13
...
Aluminium is highly electropositive metal but nitric acid renders it passive
...
Name the element of group 13 which forms only covalent compounds
...
Draw the structure of Al2Cl6
...
Mention an industrial application of silicones
...
Name a zeolite catalyst used to convert alcohols directly into gasoline
...
Electronegativity of group 13 elements is in the order B > Al > Ga > In > Tl
...
20
...
Write the isotopes of Boron
...
Write the general electronic comfiguration of group 13 and group-14
elements
...
Boron is a non-metal yet it has very high melting point why?
24
...
Why?
25
...
Why ?
2 - MARK QUESTIONS
1
...
2
...
(b) Aluminium alloys are used to make aircraft body
...
Mention two similarities and two dissimilarities between B and Al
...
What happens when :
(a) Borax is heated strongly
...
5
...
Explain why BCl3 molecule has zero
dipole moment ?
6
...
Write chemical reactions to justify amphoteric nature of aluminium
...
The +1 oxidation state in group 13 and +2 oxidation state in group 14 become
more and more stable with increasing atomic number
...
Arrange the hydrides of group 14 elements in increasing order of :
(a) thermal stability
(b) reducing power
10
...
Give appropriate reason
...
Account for the following :
(a) CO2 is a gas while SiO2 is a solid at room temperature
...
12
...
How it can be synthesized ?
13
...
[XI – Chemistry]
90
14
...
15
...
(b) In group 14, the tendency for catenation decreases with increasing
atomic number
...
List two important properties in which boron differs from the rest of the
members of group
...
2
...
Identify X, Y and Z in the following chemical equations :
Z + 3LiAlH4 X + 3LiF + 3AlF3
X + 6H2O Y + 6H2
X 3O 2 B2 O3 3HO 2
[Ans
...
Select the member(s) of group 14 that :
(a) forms the most acidic dioxide
...
(c) used as semiconductor
...
(a) What are allotropes ? Sketch the structure of two allotropes of carbon
namely diamond and graphite
...
6
...
Suggest a reason as to why CO is poisonous
...
Give suitable reasons for the following :
91
[XI – Chemistry]
(a) CO2 turns lime water milky, but if passed for a long time, the solution
becomes clear again
...
(c) Graphite is a good conductor of electricity but diamond is insulator
...
A salt A, gives the following results :
(a) It aqueous solution is alkaline to litmus
(b) It swells up to a glassy material B on strong heating
...
H2SO4 is added to a hot solution of A, white crystals an
acid C separates out
...
9
...
(c) A boron carbide rod is used in nuclear reactor
...
(i) How orthoboric acid is prepared? Give its structure
...
(b) It is heated
...
Give reasons of the following –
(a) In diborane, two B–H–B bonds are different from common covalent
bonds
...
(c) Quarts is used to develop extremely accurate clocks
...
(a) Draw the structure of diborane
...
Explain your answer with the help of
lead chlorides
...
Assign a reason for this
...
(a) Account for the following :
(i) The first ionization enthalpy of carbon is greater than that of boron
but the reverse is true for second ionization enthalpy
...
(iii) Gallium has higher ionization enthalpy than aluminium
...
370 K
Compare the general trends in the following properties of the elements in
groups 13 and 14 :
(a) Atomic size
(b) Ionization enthalpy
(c) Metallic character
(d) Oxidation states
(e) Nature of halides
4
...
Compound (A) is soluble in dilute HCl to form compound (C)
...
Identify (X), (A), (B), (C) and (D)
...
5
...
(b) Conc
...
(c) Aluminium utensils should not be kept overnight
...
(e) A mixture of diture NaOH and aluminium pieces is ased to open drain
...
Name the following —
(a) The crystalline form of silica used in modern-radio and T
...
broadcasting
and mobile-radio communication!
(b) The oxide of carbon which forms a complex with haemoglobin 300
times more faster than O2
...
(d) Group 13 element which is used to measure high temperature !
(e) A type of polymer which is semiorganic in nature !
93
[XI – Chemistry]
UNIT-12
IUPAC NOMENCLATURE
(1) Longest Chain Rule :
Longest chain in molecule is selected
...
1 2 3 4 5 6 7 8 9
C–C–C–C–C–C–C–C–C
C
C
Case (I) C
9 8 7 6 5 4 3 2 1
C–C–C–C–C–C–C–C–C
C
C
Case (II) C
In case (I), the sum of locants (2 + 6) is lower than the sum of locants (4 + 8)
in case (II)
...
”
(3) The names of side chains and the substituents are then prefixed to the name
of parent alkane and position of substituents is indicated by appropriate
numbers
...
(4) Alphabetical arrangement of side chains/substituents :
Thus, the name for compound shown above is : 6–ethyl–2–methyl nonane
...
e
...
(5) We write di, tri, tetra, penta for two, three, four, five identical subtituents
and so on
...
Note that di, tri,
[XI – Chemistry]
94
tetra, penta, hexa etc do not determine the alphabetical order of the
subtituents
...
6 5 4 3 2 1
CH3–CH2–CH–CH–CH2 –CH3
1 2
3 4 5 6
CH3 C2H5
3- Ethyl - 4 - methyl hexane and not 4- ethyl - 3- methyl hexane
(b) The name of complex chains (substitued substituents) are enclosed in
parentheses and numbering of C-atoms is carried such that the C-atom of
substituted substituent attached to main chain is given number 1
...
For example,
CH2Cl
|
Cl–CH2–C–CH2–Cl
|
CH2Cl
1, 3-Dichloro-2, 2-bis (chloromethyl) propane and IUPAC name of DDT is
Cl—
—CH—
—Cl
|
CCl3
-1, 1,1-trichloroethane 2, 2-bis (4-Chlorophenyl)
95
[XI – Chemistry]
(d) Name of a substituted substituent is considered to begin with the first
letter of its complete name
...
H2C = CH CH2CH3
:
But-1-ene and not 1-Butene
H3C C C CH2CH3
:
Pent-2-yne and not 2-pentyne
(b) When two or more similar multiple bonds are present, suffix ‘a’ to the
root word
...
g,
CH2 = CH CH CH :
But-1-en-3-yne
(d) When double and triple bonds are present on different positions, lowest
sum rule will be followed and the compound is named as alkenyne,e
...
,
HC C CH2CH = CHCH2CH2CH3
Oct-4-en-1-yne
Functional groups : The groups which determine the properties and
functions of an organic compound are known as functional groups
...
e
...
CHARACTERISTICS (FUNCTIONAL) GROUPS
Suffixes and prefixes for some important characteristic groups in IUPAC
nomenclature (in alphabetical order)
...
Class
Formula
Acid halides
CO-halogen
(C)O-halogen
[XI – Chemistry]
Prefix
96
Suffix
halodarbonyl
carbonyl halide
-oyl halide
Alcohols, Phenols
Aldehydes
OH
CHO
(C)HO
Amides
CO-NH2
(C)O-NH2
Amines
NH2
Carboxylates
COO
(C)OO
Carboxylic acids
COOH
(C)OOH
Ethers
OR
Ester (of carboxylic acids) COOR
(C)OOR
Ketones
> (C) O
Nitriles
CN
CN
Salts (of carboxylic acids) COOM+
hydroxyformyloxocarbamoyl
aminocarboxylato
carboxy
(R)-oxy-
Sulphonic acids
sulpho
SO2–OH
-ol
-carbaldehyde
-al
-carboxamide
-amide
-amine
-carboxylate
-oate
-carboxylic acid
-oic acid
(R)oxycarbonyl- (R)
...
oate
-one
-carbonitrile
-nitrile
(cation)
...
CH3CH2OH
:
ethanol
HOCH2CH2OH
:
ethane-1, 2-diol
Here ‘e’ is retained since first letter of diol, i
...
, ‘d’ is a consonent
...
OH
|
BrCH2CH2CH2CHCH3 : 5-bromopentan-2-ol
When two or more functional groups are present, the order of preference is :
COOH SO3H > ( CO)2O > COOR' > COX > CONH2 > CN
O
||
> CHO >– C NH2 > C C > C C
97
[XI – Chemistry]
•
When two or more functional groups are present, name of higher order
functional group is suffixed and the rest are prefixed
...
,
In cyclic compound, the word ‘cyclo’ is prefixed and lowest sum rule is
applied for prefixing the side chains/substituents
...
CH3
Benzene
CH2–
Toluene
CH2OH
Benzyl
Benzyl alcohol
CH2Cl
CHO
Benzyl chloride
Benzaldehyde
99
[XI – Chemistry]
COOH
CH3
CH3
o-/p-/m-xylenes
Benzoic acid
O
C
COCH3
Acetophenone
Benzophenone
OH
NH2
Phenol
Aniline
CN
OCH3
Benzonitrile
•
Anisole
When a chain of two or more carbon atoms having a functional group or a
multiple bond is attached with the benzene ring, then ring is taken as
substituent and is names as phenyl group, e
...
,
CH2CH2OH
CH2CH2CHO
2-Phenylethan-1-ol
3-Phenylpropanal
When the benzene ring is further substituted, then the name of the substituted
phenyl group is enclosed in parentheses for example :
CH2CH2OH
CH2CH2CHO
Br
3-(4-Bromophenyl) propanal
Br
2-(3-Bromophenyl) ethan-1-ol
[XI – Chemistry]
100
Purification and Characterization of Organic Compounds
(1) Lassaigne’s test for nitrogen : Lassiagne’s extract is heated with FeSO4
solution in presence of alkali, the solution is cooled and acidified with
dil
...
If a green or blue colouration is obtained, it confirms the
presence of N in the organic compound
...
ferrocyanide
3Na4 Fe CN6 4Fe3+
Fe Fe CN 6
4
12Na +
3
Ferric ferrocyanide (Prussian Blue)
This test is very delicate and is given by all compounds containing C and N
...
do not respond to this test since they do
not contain carbon
...
Na
C NS
From organic compound
+
Fe3+ N a SC N
NaSCN
Sod
...
sulphocyanide
Fe SCN
2
Na +
Ferric thiocyanate (blood red colour)
(2) Detection of sulphur : If S is present, during fusion with Na metal, Na2S is
formed which may be tested as follows :
(i) With sodium nitroprusside, violet colouration is produced
...
of PbS is formed
...
)
(3) Detection of halogens :
(a) Lassaigne’s test : When the organic compounds is fused with Na metal,
the halogens combine with Na to form sodium halides
...
(i) A white ppt
...
HNO3 indicates
chlorine
...
partially soluble in ammonia indicates bromine
...
insoluble in ammonia indicates iodine
...
HNO3 to decompose any cyanides or sulphides, otherwise these
will form ppt
...
(4) Detection of phosphorus : Phosphorus is detected by fusing the organic
compound with sodium peroxide when phosphorus is converted into sodium
phosphate
...
12MoO3
21NH 4 NO3 12H 2 O
...
HNO 3
and then ammonium molybdate is added
...
or
colouration due to the formation of ammonium phosphomolybdate indicates
the presence of phosphorus
...
C 2CuO CO 2 2Cu;
2H CuO H 2O Cu
12 Mass of CO 2 formed
100
44 Wt
...
of substance taken
(6) Estimation of Nitrogen :
Percentage of carbon
(a) Dumas method :
[XI – Chemistry]
102
C 2CuO CO 2 2Cu;
2H CuO H 2O Cu
N CuO N 2 Small amounts of oxides of nitrogen
Oxides of nitrogen Cu CuO N 2
Percentage of nitrogen
Vol
...
of substance taken
(b) KJELDAHL’s Method :
2NaOH
Organic compound H2SO4 (NH4 )2 SO Na SO 2NH 2H O
2 4
4
3
2
2NH3 H 2SO 4 (NH 4 ) 2SO 4
Percentage of nitrogen
1
...
of acid used Basicity of the acid
Mass of substance taken
(7) Estimation of Halogens : Carius method :
Percentage of chlorine
35
...
5 Mass of substance taken
Percentage of bromine
80
Mass of AgBr formed
100
188 Mass of substance taken
Percentage of iodine
127
Mass of AgI formed
100
235 Mass of substance taken
Percentage of sulphur
32 Mass of BaSO4 formed
100
233 Mass of substance taken
(8) Estimation of Phosphorus : A known mass of the organic compound is
heated with fuming HNO3 in a Carius tube when P of the organic compound
is oxidized to H3PO4
...
Percentage of phosphorus
62 Mass of Mg 2P2O 7 formed
222 Mass of substance taken
103
[XI – Chemistry]
ORGANIC CHEMISTRY
1
...
(e)
H
Br
CHO
Write IUPAC names of the following organic compounds :
O
||
(b) CH 3 C CH 2COOH
OH
(a) H2C CH CH2NH2
(c) HO CH 2 C H CH2 OH
|
OH
CHO
(e)
(d)
Br
|
(g) HOOC CH C CH 2 CHO
3
...
Draw the structures of the following organic compounds :
(a) 2,2-dimethylhexane
(c) 2-methylpropan-2-ol
(e) pent-3-enoic acid
(g) ethylproponoate
(i) 4-hydroxybutanenitrile
5
...
Define the following terms with suitable examples :
(a) Nucleophile
(b) Electrophile
(c) Free radicals
(d) Carbocation
(e) Carbanion
7
...
Which of the following carbocation is most stable :
(a)
+
C
(b) CH3 3 C C H2
(c) CH3 3 C
(d) CH 3CH 2 C H 2
(e) H 3C C H CH 2 CH 3
Arrange the above carbocations in the decreasing order of their stability
...
Explain the following technique of separation of organic compounds with
suitable examples :
(a) Crystallization
(b) Distillation
(c) Sublimation
(d) Chromatography
(e) Differential extraction
10
...
Explain the reason for the fusion
of an organic compound with metallic sodium for testing nitrogen, sulphur
and halogens
...
Name a suitable technique of separation of the components from a mixture of :
(a) calcium sulphate and camphor
(b) water and aniline
(c) a mixture of dyes
(d) copper sulphate and sodium chloride
(e) a mixture of amino acids
(f) glycerol and spentlye in soap industry
...
Explain the terms inductive effect and electromeric effect
...
Write the isomerism among the following compounds :
(a) CH3CH2CH2CH2CH3 ,
CH3
|
CH3–CH–CH2CH3
CH3
|
H3–C–CH3
|
CH3
OH
|
(b) CH3CH2CH2OH and CH3CH–CH3
O
||
(c) CH3CH2CHO and H3C–C–CH3
(b) CH3–O–CH2CH2CH2CH3 and CH3CH2OCH2CH3
O
OH
||
|
(e) CH3–C–CH2COOC2H5 and CH3–C = CHCOOC2H5
14
...
13%, H = 8
...
Calculate the empirical formula of the compound
...
C3H8O3]
15
...
39%, H = 1
...
97%, O = 23
...
Molar mass of the
1
co m p o u n d w as fo u n d to b e 2 7 6 g m o l
...
[Ans
...
0
...
320 g of silver bromide
...
[Ans
...
6%]
17
...
50 g of an organic compound was treated to Kjeldahl’s method
...
5M H3SO4
...
5M NaOH for neutralisation
...
[Ans
...
A welding fuel gas contain carbon and hydrogen only
...
38 carbondioxide, 0
...
A volume of 10
...
6 g
...
An organic compound on analysis gave following data
(i) 0
...
37g CO2 and 0
...
(ii) 0
...
T
...
Calculate the parcentage of C, H and N in compound
...
•
Wurtz reaction : Treatment of alkyl halides (X = Cl, Br, I) with sodium in
dry ethereal solution to form symmetrical alkanes having double the number
of carbon atoms as present in parent alkyl halide
...
•
Kolbe’s electrolysis of sodium or potassium salt of carboxylic acid produces
alkane having one carbon atom less than the parent acid
...
Monochlorination of 2-methyl butane gives four products
...
Unsymmetrical alkynes having no terminal hydrogen is reduced by Na/liquid
N H 3 to form trans-alkene
...
(-carbon is the carbon atom which is
next to carbon to which halogen is attached) to form more stable alkene
having more substituted double bond
...
Therefore, the base, tert-butoxide remove more exposed 1º hydrogen atom from
-carbon
...
KOH alc
H3C – CH 2 – CH – CH 3 H 3C – CH 2 – CH CH 2
|
F
Acid Catalysed Dehydration of Alcohols : Dehydration of 1º alcohols is
an Elimination reaction
...
CH3
CH3
+
+
H
CH3 CH2 C CH2 OH
CH3 CH2C CH2 – OH2
H
H
–H2O
CH3
CH3 CH2 C
+
CH2
CH3
CH3 CH2 C
H
+
CH2
H
(1º Carbocation, less stable)
+
–H
CH3
CH3 CH2 C = CH2
(Less substituted alkene, less
stable) (minor product)
111
H– shift
H
CH3
+
CH3 CH–C–CH3
(3º carbocation, more stable)
+
–H
[XI – Chemistry]
+
–H
CH3
CH3 CH = C– CH3
(More substituted alkene,
more stable) (major product)
Similarly acid catalysed dehydration of 2-methylbutan-2-ol forms
2-methylbut-2-ene as major product and 2-methylbut-1-ene as a major product
...
Larger alkyl group polarise the -bond
...
H attacks first and generate more stable carbocation
...
Brattacks to carbocation to form product
...
O
O
O
||
||
||
h 2C H –C–O 2C H +CO
C6H5–C–O–O–C–C6H5 6 5
6 5
2
One free radical always generate another free radical
...
Mechanism :
Step 1
...
CH 3Cl AlCl3 Al C l 4 C H 3
Step 2
...
Abstraction of H+ by the nucleophile
CH3
CH3
H
+
–
+ AlCl4
+ AlCl3 + HCl
Some special cases of friedel-crafts reaction
113
[XI – Chemistry]
(1) More stable carbocation will form the major product, e
...
,
CH3 CHCH3
+ CH3 CH2 CH2 Cl
AlCl3
+ HCl
Cumene
–
CH2 CH2CH2Cl + AlCl3
–
–
AlCl4 + CH3CHCH2
–
H
CH3 –CH –CH3
shift
H
1º carbocation
(Less stable)
2º carbocation
(more stable)
CH3
H3C– C–CH3
+ (CH3)2 CH2 CH2 Cl
(CH3)2 CHCH2 Cl
AlCl3
AlCl3
+ HCl
CH3
–
+
AlCl4 + CH3 –C – CH2
–
–
H
(CH3)3 C
shift
H
Directive influence of a functional group in monosubstituted benzene :
Activating groups like NH2, NHR, NR2, NHCOCH 3, OCH3,
CH3, CH2CH3 are o-/p-directors
...
But the halogen atom increase the electron availability at o-and/or/p-positions
by electron donating resonance effect
...
Deactivating groups such as NO2, CN, CHO, COOH, COR,
CONH2, COOR and SO3H are m-directing groups
...
Write IUPAC names of the following organic compounds :
OH
O2 N
NO2
(a)
(b) (CH3)4C
NO2
[XI – Chemistry]
114
OH
(c)
(d) CH3 2 CH C CHC CH3
||
O
OH
|
(e) CH3CH2 C H CH2 –CH2 OH
COOH
(g)
3
COOH
(f) |
COOH
(g) CH2 CH CH2 C CH
CH3
(h) CH3 C(CH3)2 CH CH2 (i) CH3 CH CH CH2COOH
2
...
Explain the following reactions with suitable examples :
(a) Wurtz reaction
(b) Kolbe’s electrolysis
(c) Friedal Craft reaction
115
[XI – Chemistry]
4
...
Write the conformations of ethane
...
Name the most stable conformer of ethane
...
State Markovnikov rule
...
Write
the product when the same reaction is carried with HBr in presence of
Benzoyl peroxide
...
6
...
How will you carry out following conversions :
(a) Ethyne into propyne
(b) Ethyne into benzene
(c) Benzene into 4-nitrobromobenzene
(d) Benzene into n-nitrochlorobenzene
(e) But-2-ene into ethanol
(f) Benzene into acetophenone
(g) Benzene into 4-nitrotoluene
(h) Ethane into ethyne
[XI – Chemistry]
116
(i) Ethanoic acid into methane
(j) Methane into ethane
8
...
9
...
10
...
Explain the mechanism
of electrophilic substitution in the following steps :
(a) Generation of electrophile
(b) Formation of carbocation intermediate
(c) Removal of proton from carbocation intermediate
11
...
(b) Wurtz reaction is carried in dry ether
...
(d) C-C bond length in benzene ring is 139 pm which is in between C-C
single bond 154 pm and C=C double bond 133 pm
...
(f) trans-2-butene has higher m
...
than cis-isomer
...
(h) Ethyne is more acidic than ethene and ethane
...
(j) OH is activating group while halogens are deactivating group,
however, both are o-/p-director
...
Give one chemical test to distinguish between compounds of the following
pairs:
(a) Ethane and ethene
(b) Ethene and ethyne
117
[XI – Chemistry]
(c) Benzene and cyclohexene
(d) But-1-yne and But-2-yne
(e) But-1-yne and Buta-1, 3-diene
13
...
C6H10
...
Suggest
suitable structural formulae for compound A and B
...
(a)
CH3 – CH2 – C(CH3 ) – CH – CH2
Br Br
(b) CH3 – CH2 – CH(CH3) – C CH]
14
...
Draw the structure of
alkene and write the chemical reaction involved
...
C = CH – CH2 – CH3 ]
H2
15
...
(i)
(ii)
= CH2 (iii)
16
...
When ‘A’ is oxidised with KMnO4, a single carboxylic acid
‘B’ containing three carbon atoms is obtained
...
[Ans
...
Write the structures of all possible position and chain isomers of hex-1-yne
...
Show the formation of sigma and pi bonds in ethyne
...
A hydrocarbon C5H10 does not react with chorine in dark but gives a single
monochloro compound C5H9Cl in bright sunlight
...
20
...
Which of them is
more polar and why ?
[XI – Chemistry]
118
UNIT-14
ENVIRONMENTAL CHEMISTRY
(1) Main regions of the atmosphere are (i) troposphere, (ii) stratosphere, (iii)
mesosphere and (iv) thermosphere
...
(3) Pollutants can be (i) gaseous air pollutants (e
...
, SO2, NO2, CO2, H2S,
hydrocarbons, ozone etc
...
g
...
)
(4) Green House Effect : Warming of the earth by absorption and re-emission
of solar radiations is called green house effect
...
(5) The word smog is a combination of smoke and fog
...
Classical smog is a mixture of smoke, fog and sulphur dioxide
...
The common components of photochemical smog are O3, NO, acrolein,
formaldehyde and peroxyacetyl nitrate (PAN)
...
O3 and NO irritate the nose and throat and their high
concentration causes headache, chest pain, dryness of the throat, cough and
difficulty in breathing
...
(6) In 1980, Ozone hole was detected over south pole
...
The most serious effect of the depletion of ozone layer is that
the ultraviolet radiation coming from the sun can pass through the
stratosphere and reach the surface of the earth and can lead to ageing of
skin, cataract, sunburn, skin cancer, killing of many phytoplanktons, damage
to fish productivity etc
...
119
[XI – Chemistry]
(8) The amount of oxygen required by bacteria to break down the organic matter
present in a certain volume of a sample of water is called BIOCHEMICAL
OXYGEN DEMAND (BOD)
...
(9) The International standards for drinking water are given below and these
must be followed :
Ions
Maximum limit
Harmful Effects
F
1 ppm
72 ppm causes brown mottling of teeth
...
1 - MARK QUESTIONS
1
...
2
...
3
...
Explain
...
Name the pollutant gas that causes stiffness and fall off flower buds in plants
...
Name the gas responsible for irritant red haze in the traffic and congested
places
...
Mention the effect of increased concentration of carbondioxide in
atmosphere
...
Define Biochemical Oxygen Demand
...
Name the compound responsible for ozone layer depletion in the stratosphere
...
Why classical smog is also called reducing smog
...
Describe ‘blue baby’ syndrome
...
2
...
List the gases responsible for green house effect
...
Write the chemical reaction involved in the formation of photochemical
smog
...
Write the reaction involved for ozone layer depletion in the stratosphere
...
Discuss the effects if green house gases were totally missing in the earth’s
atmosphere
...
Define pesticides and herbicides with examples
...
Domestic waste can be used as manure
...
8
...
Write the effect of the following gases on human being :
SO2, NO2, CO, CO2
10
...
Classify the following particulate pollutants as
viable or non viable : Smoke, dust, mist, moulds
...
2
...
4
...
6
...
Suggest the measures to control water
pollution
...
Suggest the effort you will make
for controlling soil pollution
...
How will it help decrease environmental
pollution ?
Discuss waste management
...
2
...
4
...
6
...
Question no
...
Question no
...
Question no
...
Question no
...
Use log tables it necessary, use of calculators is not allowed
...
What happens when sodium metal is dropped in water? (1 Mark)
2
...
Explain why BeH2 molecule has zero dipole moment although the
Be-H bonds are polar?
(1 Mark)
4
...
(1 Mark)
5
...
Write the correct IUPAC name of the compound given below:
CH2 = CH – C CH
[XI – Chemistry]
122
(1 Mark)
(1 Mark)
(1 Mark)
7
...
Name any two gases responsible for greenhouse effect
...
Arrange the following ions in order of increasing ionic radius:
K+, P3–, S2–, Cl–
...
(1 Mark)
(2 Marks)
10
...
A sample of gas occupies 3
...
Calculate the volume the
gas will occupy if the pressure is changed to 1
...
(2 Marks)
12
...
(2 marks)
13
...
Al NaOH H 2O
(ii)
SiCl 4 (l) H 2O(l)
(2 Marks)
(2 Marks)
Explain :
(2 Marks)
(i) Alkali metals are soft and can be cut with help of a knife
...
15
...
(1 Mark)
(b) Why alkali and alkaline earth metals cannot be prepared by
chemical reduction methods?
(1 Marks)
16
...
(2 Marks)
17
...
Also give reasons for this behaviour
...
50 kg of N2(g) & 10
...
Also, calculate the amount of NH formed
...
Mohan was going with his friend Soham on a motorcycle
...
On the way, a Policeman
stopped them and asked them to show pollution check certificate
...
After reading this passage answer the following questions :
(i) Why did Policeman Challan their vehicle?
(ii) What human values do you associate with the act of Policeman?
20
...
37 × 1014 S–1
...
21
...
(Z=29)
n 1, l 0, m1 1, ms
(ii)
22
...
(ii) Why is NF3 trigonal pyramidal while BF3 is trigonal planar,
though both are tetra atomic molecules?
(iii) State the hybridization of 3rd & 4th Carbon atom
O
23
...
4kJ
Indicate the direction in which the equilibrium will shift when:
(i) Concentration of SO2 is increased
...
(iii) Temperature is increased
...
Define :
(3 Marks)
(i) Common ion effect
(ii) Buffer Solution
(iii) pH
[XI – Chemistry]
124
25
...
Explain why:
(3 Marks)
C+
+
+
(i) (CH3)3
is more stable than CH3CH2 and CH3 is the least
stable cation
...
(iii) Nitric acid is added to sodium extract before adding AgNO3 for
testing halogens
...
(i) 0
...
4950
g of carbon dioxide and 0
...
Calculate the
percentage of C and H in it
...
(i) In a process, 701 J of heat is absorbed by a system and 394 J
of work is done by the system
...
Calculate the
value of G
...
0 J mol-1 K–1; T = 300 K(5 Marks)
OR
(i) Calculate lattice energy for the change
Li (g) Cl (g) LiCl(s)
Given that:
sub H of Li = 160
...
34 kJ/mol
ie H of Li(g) = 520
...
26 kJ/mol
f H of LiCl(s)= –401
...
5 kJ & S 34
...
29
...
Write the
chemical reactions for the reaction
...
Why?
(iii) Boric acid is not protic acid
...
Why?
(5 Marks)
OR
When a metal X is treated with NaOH a white precipitate (A)
is obtained, which is soluble in excess of NaOH to give soluble
complex (B) Compound (A) is soluble in dilute HCl to form
compound (C)
...
Identity (X), (A), (B), (C) &
(D)
...
30
...
1
(c) Hydrogen atoms of ethyme are acidic in nature, why?
1
OR
(a) Complete the following reactions:
(i)
+ H2SO4
(fuming)
(ii)
CaCO 2 H 2O
[XI – Chemistry]
126
1
1
dil KMnO
4
CH2 = CH2 + H 2 O O
273 K
(iii)
1
(b) –NO2 group attached to benzene is meta directing but-OH group
is ortho and para directing
...
When sodium metal is dropped in water, hydrogen gas is evolved
which catches fire
(½ Marks)
2Na 2H 2O 2NaOH H2
(½ Marks)
Ans 2
...
BeH2 is a linear molecule with H-Be-H bond angle as 180°
...
(1 Marks)
Ans 4
...
Tritium
(1 Marks)
Ans 6
...
Sp2
(1 Marks)
Ans 8
...
K+ < Cl– < S2– < P3–
(1 Marks)
Reason : All the ions are isoelectronic with 18 electrons
...
This results in the
decrease in lonic radii
...
(1 Marks)
Ans 10
...
E of Be is greater than Born of because of :-
(2×1 Marks)
(1) Electronic configuration : Be have fully filled stable configuration, so difficult to remove electron
4 Be
5B
1s 2 2s 2
1s 2 2s 2 2p1
127
[XI – Chemistry]
(2) Penetration effect : In case of Be, electron is to be removed
from s-subshell while in Boron from p-subshell penetration effect
of s is greater than p so difficult to remove electron from Be
...
The given question is based on Boyle’s Lao
...
45atm × V2 L
760 torr/atm
V2 = 2
...
Unit of a is atm lit2 mol–2 and of b is lit mol–1
Ans 13
...
(i) Alkali metals have large atomic size with only one valence
electron
...
Because of weak metallic bonding, alakli
metals are soft and can be cut with a knife
...
Smaller is
the ionization enthalpy, greater is the reactivity
...
Thus, the ionization enthalpy
of potassium is less than sodium
...
(1 Mark)
Ans 15
...
(1 Mark)
Ans 16
...
These empty d orbitals of Si can accept lone pair of electrons from
water molecule
...
(½ Mark)
[XI – Chemistry]
128
Cl
Si
+
Cl Cl Cl
H
...
Cl
–HCl
H
Si
Cl Cl OH
OH
+3H2O
–3HCl
Si
HO
OH
HO
(½ Mark)
Carbon atom on the other hand does not have any vacant d-orbitals
in its valence shell
...
Thus, CCl4 dose not hydrolyse
...
The decreasing order of acidic behaviour is:
Ethyne > benzene > n-pentane
(1 Mark)
The C–H bond in ethyne, benzene and n-pentane are formed by
sp–s, sp2–s and sp3–s overlap
...
Therefore, sp-hybridised carbon in
ethyne is more electronegative then sp2 hybridised carbon of benzene
which in turn is more electronegative than sp3 hybridised carbon of npentane
...
Moles of N2 Molar mass
50 103 g
28 g/mol
= 1
...
0 × 103 mol
N2 (g) + 3H2 (g) = 2NH3 (g)
(Eqn 1)
According to equation (1),
1 mole of N2 (g) reacts with = 3 moles of H2 (g)
Therefore 1
...
786 103
moles of H2 (g)
1
= 5
...
0 × 103 mol of H2 (g) only
...
(½ Mark)
To calculate the amount of NH3 formed,
3 moles of H2 (g) give = 2 moles of NH3 (g)
Therefore,
5
...
3
...
3 × 103 × 17 g of NH3
= 56
...
(i) The exhaust of motorcycle was producing smoke which causes
air pollution
...
The are very harmful
air pollutants
...
He was not only doing his duty but was
helping to maintain clean environment which is the need of the
hour
...
(½ Mark)
Ans 20
...
37 1014 s1
= 0
...
18 1018 2 2
n n
1 2
(½ Mark)
1
1
2
...
18 1018 J
36
(½ Marks)
E –2
...
11 1018 J
6
...
18 × 1015 s–1
= 3
...
(i) For n = 1,
Value of l = n – 1
=1–1
=0
For each value of l,
Value of ml = –1,
...
, + l
131
(1 Mark)
[XI – Chemistry]
Therefore,
For n = 1, l = 0,
ml = 0
Thus the value of ml =1 is not possible
...
(i) Resonating structure of O3 molecule
(ii)
(1 Mark)
O
O
O
O
O
O
In NF3, N atom involves Sp3 hybridization and one position is
occupied by a lone pair
...
But in BF3, B in involves SP2 hybridization having
trigonal planar geometry
...
(1 Mark)
(iii) C3 Sp3
C4 SP
(½ × 2 Marks)
Ans 23
...
(1 Mark)
(ii) If the concentration of SO3 increased the equilibrium will shift
in the backward direction to consume the product SO
...
(1 Mark)
Ans 24
...
(1 Mark)
(ii) Buffer Solution : Buffer solution is that which resist the change
in pH on addition of small amount of acid or base in it
...
(1 Mark)
Ans 25
...
–2
0
0
H2S + Cl2 S
–1
+ Cl–
(½ Mark)
Step 2 : The half reaction are :
Oxidation half reaction : H2S S
Reduction half reaction : Cl2 2Cl–
(½ Mark)
Step 3 : Balance oxidation number by adding electrons
...
So, balance the hydrogen atoms
...
Oxidation half reaction : H2 S S + 2e– + 2H+
Reduction half reaction : Cl2 + 2e– 2Cl–
(½ Mark)
Step 5 : Add the two reactions to get a balanced redox reaction
...
(i) (CH3)3 C+ is stable due to hyperconjugation but CH3+ lacks
hyperconjugation stability
...
(1 Mark)
(iii) Conc
...
(1 Mark)
Na2S + H+ Na+ + H2S
NaCN + H+ Na+ + NCN
133
[XI – Chemistry]
Ans 27
...
2457 g
Mass of CO2 produced = 0
...
2025 g
% of C
Mass of CO 2
12
100
44 Mass of compound taken
% of H
Mass of H 2O
2
100
18 Mass of compound taken
2
0
...
2475
9
...
4950
100 54
...
2475
(1 Mark)
(ii) Blood red colouration due to Fe (CNS) will be produced
...
(i) Heat absorbed by the system (q) = + 701 J
(½ Mark)
Work done by the system (w) = –394 J
(½ Mark)
Change in internal energy (U) = q + w
(½ Mark)
= 701 – 394
= + 307 J
(ii) G = –2
...
0 JK–1 mol–1
T
(½ Mark)
= 10
G = – 2
...
303 × 8
...
2 Jmol–1
(1 Mark)
OR
[XI – Chemistry]
134
Ans 28
...
66 – (160
...
07) –
1
(244
...
26)
2
lattice H – 839
...
5 kJ, n (g) = – 1mol,
R = 8
...
5 –1mol 8
...
5 kJ–2
...
978 kJ
(½ Mark)
G = H – TS
(½ Mark)
= – 12978 J – 298 ( – 34
...
8
= – 2816
...
(½ Mark)
Ans 29
...
Na2 B4O7 + 2HCl + 5H2O 2 NaCl + 4H3BO3
(1 Mark)
(ii) Pb (IV) state is unstable due to inect pair effect
...
(1 Mark)
(iv) Carbon is able to form p-pbond with O atom and constitute
a stable non-polar molecule O = C = O
...
(1 Mark)
Si on the other hand is not able to from pp-pp bond with O
atoms because of its relatively large size
...
(1 Mark)
OR
Ans 29
...
HCl
AlCl3
Soluble
(C)
NaOH
NaAlO2
Soluble
(B)
Al2O3
(D)
2 Marks for writing reactions
1 Marks for identifying X
½ mark each for correctly identifying A, B, C and D
...
(a)
anhyd
...
AlCl3
+ CH3Cl
(ii)
CaO
CH4 1
NaOH
CH3CH2CH2CH2CH = CH2 + HBr CH3CH2CH2CH2CH2CH2Br
(iii)
(c)
HNO3
H 2SO4
NO2
1
(b)
CH3
CH3 COOH + NaOH CH3COONa
The H attached to sp hybrid carbon becomes acidic due to high
electronegativity of (sp hybridised)
...
+
OH
OH
+
+
OH
OH
–
OH
–
–
The electron density increase on o- and p- positions, therefore
electrophile attacks on o- and p- positions
...
All questions are compulsory
...
Question no
...
3
...
6 to 10 are short answer questions and carry 2 marks
each
...
Question no
...
5
...
23 is value based question carrying 4 marks
...
Question no
...
7
...
QUESTIONS
1
...
Write IUPAC name and symbol of element having atomic no
...
What is absolute zero?
4
...
Define residual entropy
...
Commercially available sulphuric acid contains 93% acid by mass
and has density of 1
...
Calculate its molarity
...
Which out of NH3 and NF3 has higher dipole moment and why?
(2 Marks)
8
...
4 KJ
What is the standard enthalphy of formation of NH3?
9
...
(i)
Write IUPAC name of CH 3 CH 2 CO CH 2 CHO
...
3
11
...
12
...
An electron has a speed of 600 m/s with uncertainty of
...
What
is the uncertainty in locating its position?
OR
(a) Which atom is indicated by following configuration [Ne]3s23p4?
(b) How many odes are present in 3d orbital?
(c) Give an example of disproportionate reaction
...
Of the following species which one is most stable and why–
(CH3)3C+, (CH3)2CH+, CH3CH2+, CH3+
15
...
(b) Gypsum is heated to 393 K
...
16
...
139
[XI – Chemistry]
(b) Explain why cations are smaller and anions are bigger in radii
than their parents?
17
...
(b) On the basis of MOT explain why Ne2 molecule does not exist?
18
...
19
...
(c) Solution of alkali metal in ammonia is soloured?
20
...
03g of an organic
compound gave 50 ml of nitrogen collected at 300K temperature and
715 mm pressure
...
(a)
What is biochemical oxygen demand?
(b) Write down the reactions involved in ozone layer depletion?
22
...
1 × 1015 s–1 hits the metal
...
0 × 1014 s–1?
23
...
Instead the water became cloudy
...
As
a student of chemistry
...
(a) Balance and complete the following reactions–
(i)
Al NaOH H 2 O ____________
(ii)
H3BO3 ____________
(b) What is Inorganic Benzene?
(c) Name the compound used as catalyst in petrochemical industry
for cracking of hydrocarbons?
(d) Conc
...
(ii)
It swells up to glassy material Y on strong heating
...
H2SO4 is added to a hot solution of X, white
crystal of an acid Z separate out
...
25
...
00 moles of PCl5 kept in one litre closed reaction vessel was
allowed to attain equilibrium at 380 K
...
(Equilibrium constant = 1
...
3g of NaOH
in water to make 200 ml of solution?
141
[XI – Chemistry]
26
...
cis-but-2-ene and trans-but-2-ene
...
KOH _________
(ii)
CH 3 CH CH 2 HBr ___________
(iii)
C6 H5OH Zn dust __________
PEROXIDE
OR
(b) Draw Sawhorse projections of ethane?
(c) An alkene ‘A’ contains three C–C, eight C–H bonds and one
C–C bond
...
Write IUPAC name of ‘A’
...
All questions are compulsory
...
Question no
...
3
...
6 to 10 are short answer questions and carry 2 marks
each
...
Question no
...
5
...
23 is value based question carrying 4 marks
...
Question no
...
7
...
QUESTIONS
1
...
2
...
Which of the following has maximum bond angle?
H2O, CO2, NH3, CH4
4
...
5
...
Identify ‘A’ and ‘B’ in the following:
Na
Redhotirontube
A CH CH B
873
7
...
1 × 10-31 kg
...
E
...
Calculate its velocity
...
Give two differences between and bonds
...
Compare the relative stability of the following species on the basis of
molecular orbital theory and indicate their magnetic properties:
N2+ and N2-
10
...
Arrange the following:
(a)
(CH3)3C, CH3CH2CH, CH3 CH2CH2CH2
CH3
[Increasing order of stability]
(b) I, –Br, –Cl, –F [Decreasing order of –1 effect]
(c) Write structural formula of 3, 4, 4, 5, 5-tetramethylheptane
12
...
(c) Electronic configuration
13
...
(b) Sodium is stored under kerosene oil
...
14
...
15 g of an organic
compound gave 0
...
Find out the percentage of bromine
in the compound
...
Dinitrogen and dihydrogen react with each other produce ammonia
according to the chemical equation:
N 2 g 3H 2 g 2NH 3 g
(a) Calculate the mass of ammonia produced if 2 × 103 g dinitrogen
reacts with 1 ×103 g dihydrogen
...
(a) What causes the temporary and permanent hardness of water?
(b) Compare the structures of H2O and H2O2
...
(a) Write the conjugate
HCOO-?
acids for the Bronsted base NH2- and
(b) The concentration of hydrogen ion in a sample of soft drink is
3
...
What is its pH? [log 3
...
5798]
(c) Equilibrium constant for a reaction is 4
...
18
...
(b) Calculate the total pressure in a mixture of 8 g of oxygen and
145
[XI – Chemistry]
4 g of hydrogen
...
R =
0
...
19
...
20
...
(b) Oxygen has lesser first ionization enthalpy than nitrogen
...
21
...
What do you conclude for the reaction
if Qc< Kc?
(b) State Le Chatelier’s principle
...
Explain by using concept of common ion effect
...
(a) What type of isomerism is shown by pentane and 2-Methyl
(isopentane)
...
U
...
A
...
Cloroflurocarbons commonly known as Freons have the properties
such as low boiling points, odourless, non-toxic, non-flammable, least
chemical reactivity an thermally stable
...
In the group
discussion in a school, Rakesh strongly supported the use of freons
for making our life comfortable
...
24
...
?
(c) Give a brief account for the following statements:
(i)
n-pentane has greater boiling point that isopentane
...
OR
(a) An alkyl halide (X) of formula C6H13Cl on treatment with
alcoholic KOH or potassium tert-butoxide give two isomeric
alkenes Y and Z (C6H12)
...
Predict the structure of X, Y and Z
...
(a)
State Hess’s law
...
Explain
...
kJ and S 44
...
147
[XI – Chemistry]
Calculate G for the reaction and predict whether the reaction
may occur spontaneously
...
2 kJ mol–1 K–1
At what temperature will the reaction become spontaneous
considering H and S to be constant over the temperature
range
...
(c) Give one point to differentiate the following thermodynamic
terms:
(i)
(ii)
26
...
Isothermal process and adiabatic process
...
(ii)
PbCl4 is a powerful oxidising agent
...
(b) Complete the following reactions:
(i)
Na 2 B4 O7 2HCl 5H 2 O
(ii)
B2 H 6 6NH3
OR
(a) Draw the shape of B2H6 molecule
...
(c) Complete the reactions:
(i)
BF3 LiH
(ii)
(5)
H3BO3
149
[XI – Chemistry]
Title: support material for class 11
Description: detailed explanation with practice questions and solutions
Description: detailed explanation with practice questions and solutions