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2nd secondary

1

Chemistry
Second Secondary

2nd secondary

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Contents
Chapter One:
Atomic structure
...
youtube
...

https://www
...
com/watch?v=hePb00CqvP0

Chapter Three:
Bonds and forms of molecules
...
youtube
...

https://www
...
com/watch?v=-0N1ZZZRM48

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General objectives of chapter one:
1-Recognize the historical background of atomic structure
...

3-Discuss the Rutherford’s atomic model
...

5-Define the reasons of inadequacy of Bohr’s model
...

7-Explain the concept of electron cloud and orbitals
...

9-Distribute electrons of any atom considering the building
up principle and hund’s rule
...


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Chapter one

Structure of the atom
Atomic structure
1-Democritus’s (Greek philosophers) idea:
Any piece of matter can be divided into smaller parts and each part can be
subdivided into smaller parts which can't be divided this part is called Atom
...

b- He supposed that all matters composed of 4 constituents which are (water,
air, dust and fire) and postulated that the cheap metals such as iron or copper
can be changed into precious ones like gold by changing the percentage of four
constituents
...

B-He was the 1st scientist to define the element as pure simple substance which
Cannot be analyses into simple one by normal chemical methods
...

2- Every element consists of very small dense atoms which can’t be divided
...

4- Atoms of different are different
...


5 – Thomson’s model of the atom:
The scientist Thomson carried out many experiments on the electric
discharge through gases from which he had discovered the cathode rays
...


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Cathode- rays experiment
(Discovery of the electron)
High voltage 10000
vollts

Anode

Cathode
To vacuum pump

a- All gases under normal conditions of pressure and temp
(76 cm
...
25c) don't conduct electricity
...
These rays were named by (Cathode rays)
...

2) Transfers in straight lines glowing the glass facing the cathode
...

4) Have a thermal effect
...

6) Cathode rays don’t change by changing either cathode material or type
of the gas, which proves that cathode rays take part in the structure of
all substances
...


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Metal sheet covered
with ZnS

Gold foil
Source of alpha
particles

1– He allowed alpha particles to hit a metallic plate lined with Zinc sulphide
(glows when hits with alpha rays)
2– On placing a gold foil in the front of alpha rays he concluded the
following from the following observation
...

1- A very small percentage of alpha
particles reflected back to
appears as flashes on other side of
sheet
...


2- Most of the atom is a space not
solid as explained by Dalton
and Thomson
...

4- The dense parts of the atom,
which concentrate in it most
mass, have same charge of
alpha particle (+ve) which
called nucleus of the atom
...


1- The Atom:
Although it has very small size but it has a complicated structure that
resembles the solar system in which electrons revolve around the
central nucleus in orbits as planets revolve around the sun
...
Located in the centre of the atom with
(+ve) charge
...
Most mass of the atom is
concentrated in the nucleus as mass of e is very small and can be
neglected
...

2- No of electrons (-ve) equals no of protons (+ve) so the atom is
electrically neutral
...

b- Centrifugal force due to velocity of electron around the nucleus
...

Explain: Structure of the atom in the view of Rutherford
...

2- Atom is electrically neutral as no of p+ s equals to no of e's
...

4- Electrons orbit the nucleus in a rapid movement without gaining or losing
energy
...


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6- Each electron in the atom has a definite amount of energy depending on
the distance between is E
...
This energy increases as its radius
increases
...
Each level has energy expressed by a completely no called principle Q
...


Ex: The 1st E
...
no = 1
The 2nd E
...
no = 2
8- If when atom is excited by heating (Quantum) or by electric discharge
the electron will transfer to a higher E
...
The excited electron in the higher E
...


 Remarks:
1- The quantum: Is the amount of energy gained or lost when an electron
jumps from one E
...

2- The difference in energy between levels (Q) is not equal i
...
the difference in
this energy decreases further from the nucleus
...

3- The electron does not move from its level to another unless the energy
absorbed or emitted is equal to the difference in energy between 2 levels i
...

one quantum
...
Q can't be divided or doubled

Give reason: It is wrong to say that e' to be transferred from E
...
L (M)
needs amount of energy equals 2 quantum
...
L to higher ones
...

2- He introduced the idea of quantum no to detect energy of electrons in
energy levels
...


Disadvantages (Inadequacies) of Bohr's theory:
1 – If failed to explain the spectrum of any other element even that of He
except hydrogen (Simplest Electronic System)
...

3– He postulated that it is possible to determine precisely both speed and
location of an electron at the same time
...

4– He described the electron when moving in a circular planer orbit, which
means that hydrogen atom is planer
...


Bohr's Theory
The atomic spectrum
Studying and explaining the atomic spectrum was the key to his atomic
structure in 1913 and he was deserved Noble Prize in 1922
...

2 – By using spectroscope we find that this light consists of a fixed number of
colored lines called line spectrum
...


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By exp
...


N
...


The principles of Modern Atomic Theory:
1 – Dual nature of electron
...

3 – Finding the mathematical expression, which describes the wave motion
of electron, its shape and its energy?
-------------------------------

1 – The dual nature of the electron
The experimental data showed that the electron has a dual nature i
...

a) It is a material particle
...


* De Broglie principle:
Every moving body (such as electron or the nucleus of an atom or whole
molecule) is associated with (accompanied by) a wave motion (or matter
waves) which has some properties of light waves
...
We can only say that it is
probably to a greater r lesser extent to locate the electron in this or in that
place
...

3
...

 The electronic motion around nucleus has wave properties therefore the
position to use the term electron cloud to describe any orbital
...
"
 The difference between the orbit and orbital concepts according to both
Bohr and the wave mechanics theories:
Bohr s theory
Schrodinger s wave mechanics theory
 It is a circular planer orbit with
 It is an electron cloud used to
particular radii
describe any orbital
 Electron cloud the regions of
high density of dots represent
the region of high probability of
finding the ( e ) from which it is
Bohr's orbit
possible to define the atomic
radius
Probabili
ty of
finding
the
electron

Schrodinger's wave mechanics
theory

Distance from
the nucleus
R

Probabilit
y of
finding
the
electron
Distance from the
nucleus

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 The mathematical solution of the Schrodinger equation introduced four
numbers which are called quantum numbers
...
Besides, they define the energy, shape
and direction of orbital
...
no (n)
...
no (ℓ)
...
no (mℓ)
...
no (ms)
...
levels their number in the heaviest known atom in
the ground state is seven
...
level = two times the square of
the level no (2n2)
...
L
K
Is filled with
2 electrons
nd
-2 E
...
L
M
Is filled with
18 electrons
th
-4 E
...
However,
the atom becomes unstable if no of electrons exceeds 32 electrons on any
level
...
Subsidiary Q No (ℓ):
1- Used to detect the no of sub levels in each E
...

2- The energy sub levels take the symbols s, p, d, f
...
When he used a spectroscope, which has a high resolving
power, he found that the single line (which represents electron transition
between two different energy levels) is indeed a number of fine spectral
lines which represents electron transition between very near energy
levels (sublevels)
...


-1st E
...
L
-3rd E
...
L

K
L
M
N

has 1 sub level
has 2 sub level
has 3 sub level
has 4 sub level

1s
2s, 2p
3s, 3p, 3d
4s, 4p, 4d, 4f

N
...
level is not equal
...
levels also differ in energy
...


Ex: 4d>3d

4p>3p>2p

 There is a small difference in the energy between sub-levels
...
Magnetic Q No (m):
Detected by Zeeman when he exposed spectral line to strong magnetic field, he
found that each line divides into many lines, so he concluded that each E
...


- Magnetic Q No(mℓ ) is characterized by:
1- Used to detect no of orbitals in each E
...

2- Sublevel (S) has one orbital of spherical symmetrical shape
...

 Each orbital (Px,Py,Pz ) is perpendicular to the other two
...
e point of zero electron
y
density
...

5- Sublevel (f) has 7 orbital
...

Ex: px = py = pz
7- No of orbitals in each E
...
level = n2
...
No (ms):

 Detects the direction in which the electron spins around its axis during its
rotation around the nucleus
...

 It has only two possible values + 1/2 – 1/2




Give reason: Each orbital carries 2 electrons although they are negatively
charged
...
L, sub levels
orbitals and no of electrons:
1- No of energy sublevels = order of principle level (n)
...

3- No of electrons occupying a given E
...


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Ex:
Order of E
...


E
...
These rules are:
 Pauli’s exclusion principle : it states that:
 It is impossible for two electrons in the same atom to have the same four
quantum numbers
...

Ex: 4s is filled before 3d as energy of 4s < 3d
...
"

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Ex:
8O

2
2
3
7N 1s – 2s – 2p

px py py
2p   
2s 

1s 

1s

2s


1s2 – 2s2 – 2p4

2p


px


py


py


 Atom is stable when the outer sub-level is half completely filled with e's
...

2- Electrons prefer to be paired with another electron than to transfer to a
higher sub-level, as the energy needed to transfer it to a higher sub-level
...

Other E
...
Write short notes on:
1- Hund's rule
...

3- Heisenberg uncertainty principle
...
Write scientific term:
1- Area of space around nucleus which has probability for finding electron
...

3- Sublevel can be saturated with 10 electrons
...
number which detects no of orbitals and their direction in space
...
number used to detect direction of electron around its axis
...
Complete:
1- Max
...
The electrons can be distributed in
…………
...
levels …………
...
orbitals
...
In energy
...
and ………
...
Give reason:
1- It’s wrong to consider the electron as (-ve) particle only
...

3- The relation 2n2 cannot be applied to O, P and Q levels
...

5- Sub level d is filled with 10 electrons
...

(First question):

20

A- Choose the correct answer:
1- The energy sublevels that form the third energy level are --------a- s

b- s, p

c- s, p, d

d- s, p, d, f

2- The uncertainty principle was proposed by-----------------a- Heisenberg
...

C- Rutherford
...


3- The --------elements tend to reach the electron structure : ns2 , np6
a- Main transition
b- inner transition
c- noble

d- transition

B- Give reasons:
1- The atomic radius in the same group increases as the atomic number increases
...

C- Write the electronic configuration for 20 Ca by two different ways and show
the location of element in modern periodic table
...
(---------------)
2- The limited colored lines obtained from heating gases to high temperature under
low pressure
...
(-----)
4- The tendency of an atom to attract the electrons of the chemical bond to itself
...


(Third question):
A- Compare between:
1- The acidic oxides
...
Hund's rule
...

2- Electron affinity
...
6A° and the bond length of hydrogen
fluoride molecule equals 0
...


B- Show by an experiment how you can obtain the cathode rays
...

2- Arrange the energy sublevels according to building up
principle
...

4- Define the location of the four blocks of the table
...

6- Compare between the electron affinity and
electronegativity
...

8- Identify the relationship between the atomic radius and
the acidic and basic properties
...

10-Calculate the oxidation number
...


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Chapter two
Classification of elements and the long periodic table
The long form periodic table:
It depends on the building up principle (Aufbau) the elements are arranged in
an ascending order according to their atomic number (each element have one
electron more than the element before it)
...

2- P – block consists of (6) groups because the P – sublevel consists of three
orbitals which filled with six electrons
...

4- f block are separated from the table so that the table is not too wide (long)
5- The first period contains two elements because it consists of elements of
the sublevel 1S = 2 electrons
...

7- The third period contains eight elements because it consists of element of
sublevel (3S + 3P) = (2 + 6) = 8 electrons
...

9- The fifth period contains (32) elements because it consists of elements of
the sublevels (5S + 4d + 5P) = 2 + 10 + 6 = 18 electrons
...

How can you find the location and the type of element in the periodic
table?
1- Write the electronic configuration of element in quantum levels
...

Example:
Find the number of period and group for each of the following element:
Na: The atomic number = 11
Cl : The atomic number = 17

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Noble gases: They are the elements of the last column of the P – block all
their energy levels are completely filled with electrons
...

The transition elements: They are the elements of the d – block all their
energy levels are completely filled with electrons except for the two external
energy levels
...


Trends and periodicity of properties in the periodic table
The atomic radius:
We can not determine the atomic radius because electron has a wave motion
so it is impossible to determine exactly the location of an electron around the
nucleus
...

B

Rad
ius
A
B Ra

diu
sA

The bond length: It is the distance between the nuclei of two bonded atoms
...


2- Electron diffraction
...
98 Å and the
length between carbon and chloride atoms C – Cl is 1
...
Calculate the
atomic radius of carbon
...
98
‫ــــ‬
2

= 0
...
76 – 0
...
77 Å

3- The bond length in the molecule of NH3 is 1
...
6 Å
...
6‫ـــ‬
2

= 0
...
3 = 0
...
7 × 2 = 1
...

Atomic radius increases in group by increasing of atomic number why?

Because the increase in atomic number makes to increase the number of
energy level screen the attractive force of the nucleus for valence electrons
and increase the repulsion force between electrons therefore the atomic radius
increases
...
B
...

2- The anion's radius is bigger than that of its atom?
This is due to the increase in the number of the negative charges in the shells
therefore the repulsive force between the electrons increases so the shells
move a part and this leads to increasing of the anionic radius than that of its
atom
...
It has a
positive value (∆H = + ve KJ/Mole)
...

3- The ionization energy of element of group (5A)
( N7 – P15 – As33 – Sb51 – Bi83 ) is much greater than any element have the
same period because the outer most energy sublevel (P) has three electrons
and it is half filled with electrons ( nP ) and this gives the atom of the element
some extra stability so the ionization energy is greater
...


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5- Ionization energy increases period?
Because the positive nuclear charge gradually increases with the increase of
the atomic number led to decrease the atomic radius and increase the attractive
force of the nucleus on the valence electrons therefore the electrons needed m
large high energy to remove (separated) from the atom
...

7- The ionization energy of elements of group (2A) is much greater than
any element have the same period?
Because the outer most energy level (S) of the element of group (2A) is
completely filled with electron (nS2) and this gives the atom of the element
some extra stability so the ionization energy is much greater
...
R
...
In the horizontal periods electron affinity increases with the
increase in atomic number?
Due to the atomic radius (size) gradual decrease so it becomes easier for
the nucleus to attract the new electron
...
R
...
The electron affinity decreases in group?
Due to the increase of the atomic volume with increase atomic number and
this leads to the screening of the attraction force of the nucleus on the valence
electrons
...


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Elements of the fifth group (N7 , P15 ) have a lower value of electron
affinity
Because the outer most energy sublevel (nP ) has three electrons and it is half
filled with electrons it gives the atom some extra stability ( N7 : 1S2 , 2S2 ,
2P2)
...

Electron affinity of Fluorine ( F9 ) is less than that of chlorine ( Cl17 ) ?
Because the atomic radius ( size ) of fluorine atom is smaller than that of
chlorine atom and when fluorine atom gains electron it is affected by a great
repulsion force bigger than that in chlorine atom and fluorine atom is very
small size
...


Compare between ionization energy, electron affinity and electro
negativity
Ionization energy
It is the amount of
energy
needed
to
remove
the
least
connected
electron
bond in a single atom

Electron affinity
It is the amount of
energy released when
an extra electron is
added to a neutral
single atom to form an
ion
It refers to the atom in It refers to the atom in
its single state
its single state

Electro negativity
It is tendency of an
atom to attract the
electrons of chemical
bond to itself

It refers to the atoms
which linked together
in the molecule
It
is
inversely It
is
inversely It
is
inversely
proportional to the proportional to the proportional to the
atomic radius
atomic radius
atomic radius

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The
atom
losses
electrons and converted
into positive ion
It has a positive value

28

The
atom
gains
electrons and convers
into negative ion
It has a negative value
∆H = - value
type of reaction is
exothermic

Differentiation between metal and non metal
Metals
Non metals
Valence shell has less than help its Valence shell has more than half its
capacity of electrons ( 1 or 2 or 3 ) capacity of electrons ( 5 or 6 or 7 )
They one called electropositive They are called electronegative
elements
...

electricity
...
B
...

2- Metals are considered as electropositive elements because metals lose
electrons to form positive ions
...

4- Metal are good conductors of electricity because they have few valence
electrons which can transfer easily from one position to another in the metal
structure
...


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6- Metals have small values for ionization energy and electron affinity
because they have large atomic radius
...


Metalloids
1- They are elements whose valency shell contains 4 electrons
...

3- They act as semiconductors (Boron – silicon) which are used in or
transistors and knows as semiconductors electronic instruments
...

od

Metals

Metalloids increase in period because the atomic size decrease and the
attractive force of nucleus to electron will be increased therefore it becomes
easier for the nucleus to gain a new electron
...

In groups : non metals decrease because the increase in the atomic number
makes to increase the energy level and screen the attractive force of nucleus
on the valence electrons therefore it is difficult for the atom to gain a new
electron
...


Metallic prop inc

Nonmetallic prop dec

Nonmetallic prop inc
Metallic prop dec Strongest non metal

Strongest metal

Acidic – basic properties
Acidic oxides
They are non – metallic oxides
such as CO2 , SO2 , SO3 , P2O5
They dissolve in water to form
acids
Co2 + H2O
H2CO3
SO2 + H2O
H2SO3
SO3 + H2O
H2SO4
P2O5 + H2O
2H3PO4

Basic oxides
They are metallic oxides such as
Na2O , K2O , MnO , CaO , BaO
Some basic oxides dissolve in
water to form alkalis and others
are not
Na2O + H2O
2NaOH
K2O + H2O
2KOH
CaO + H2O
Ca(OH)2
MgO + H2O
Mg(OH)2
They react with alkalis to form They react with acids to form salt
salt and water
and water
CO2 + 2NaOH
Na2CO3 + H2O Na2O + 2Hcl
H2O + 2Nacl
SO2 + 2NaOH
Na2SO4 + H2O MgO + H2SO4
MgSO4 + H2O
They do not reaction with acids
They do not react with alkalis
The strength of the oxygenated acids: They are acids that contain hydrogen,
oxygen and a third element usually a non-metal
...

(n) Is the number of oxygen atoms?
(m) Is the number of hydroxyl groups?

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The strength of oxy acids are depends on the number of oxygen atoms which
does not linked with hydrogen atoms when this number increase, the strength
of the acid
...

2-They have both acidic and basic properties such as Al2O3 , ZnO , Sb2O3 ,
SnO
...

The modern definition:
valence shell of the atom
...
g
...
g
...

The oxidation number of hydrogen in its hydrides = -1 such as NaH , KH ,
CaH2
...

Such as NaCl , HCl , CuSO4
The oxidation number of any element in its pure state = zero
...
g
...

The oxidation number for any atomic group ( poly atomic ion ) = the number
of charge on the group ( ion ) such as OH- , SO4-- , CO3-- , NH4+ , PO4---
...

The Reduction process: it is the process of gaining electrons due to decrease
the oxidation number for the element
...

C2H5OH
C = -2

CH3CHO
C = +1

CH3COOH
CO2
C = zero
C = +4
Oxidation
Oxidation
Oxidation
Explain the type of change (oxidation or reduction) that of chromium and
iron in this reaction
...

The oxidation number of the elements in groups from IV to VII = the group
number = - value because the elements gain electrons to complete a full shell
...


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Questions on Chapter 2
A- Complete the following:
1- The formula of sodium peroxide is ……… and the oxidation number of
oxygen in it is
...
, and the oxid
...
of Beryllium is

...
and the oxid
...
of
nitrogen in it is …………
...
But in
superoxides is ……
...

4- The oxidation number of hydrogen in most of its compounds is
...

5- The decrease of atomic radius of nonmetals leads to the
...

B- Write the scientific term (or rule which explains each of the following
statements:
1- Half the distance between the centers of two similar atoms in diatomic
molecule
...

3-The energy required to separate electrons less in connection by single atom
in gaseous state
...

C- Choose the best answer:
1- The sublevel (d) contains
...
electron
...

(2 - 3 - 5)
3- The valency shell of the atoms of fifth group elements contain
...
block
...

a) 6
b) 16
c) 14
d) 32
6- The fourth energy level is saturated by a number of electrons equals
...

a) Up on increasing atomic number only
b) Up on decreasing atomic number only
c) Up on increasing atomic volume only
d) A and c
8- The oxidation number of hydrogen in hydrogen molecule is (1, 2, 3, 0) and
its oxidation number of hydrogen chloride is (1, 2, 3, 0)
...

a) +2
b) +l
c)-2
d)-l
10- The oxidation number of oxygen in H 2O2 is
...

a) Less
b) more c) the same
d) none of the above
-13- The oxidation number of Sulphur in (SO4) is
...

a) Increasing of atomic number only
...

c) Increasing of boiling degree
...


C- Write the scientific explanation of the following:
1
...

2
...


2nd secondary

37

3
...

4
...

5
...


it

is

impossible

to

measure

the

atomic

radius

6
...

7
...

8
...

9
...

10-Zinc oxide is called amphoteric oxide
...

2- Define shapes of molecules on the view of valence’s
electron pairs repulsion theory
...

4- Recognize the electronic theory of valency
...

6- Recognize the formation covalent bond in hydrogen and
hydrogen fluoride molecules on the basis of the valence
bond theory
...

8- Explain the overlap of hydrogen and carbon orbitals to
form methane molecules
...

3- With hydrogen: Most of elements of this group reacts with hydrogen to
form hydrides such as NH3 , PH3 , phosphine , Arsine AsH3
These compounds (NH3- PH3) can form coordinate bonds due to presence
of pair of electrons in valence shell so it can give this electrons to the
outer atoms or ions to form coordinate bond
NH3 + H+
NH4 , PH3 + H+
PH4
These compounds are basic because atom of element has one pair of
electrons donated to positive proton of hydrogen which is found in the
molecule of water therefore the negative hydroxyl group separated from
molecule of water
...

- The thermally stability and the solubility in water are decreases with
increasing the atomic in this group (NH4+) is more polarity than (PH4+) is
more polarity than (AsH4 +)

Allotropy
It is the presence of the element in more than one form having the same
chemical properties but different physical properties
...


2nd secondary

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Forms:
Solid non – metal
Phosphorus
Arsenic
Antimony

Allotropic forms
White – red – violet
...

Yellow – black
...

1- The main method ( from the atmospheric air )
2NaOH + CO2
2Cu + O2
∆

Na2CO3 + H2O
2CuO

2- From the chemical compounds:
By heating a mixture of sodium nitrite and ammonium chloride
solutions
...


nitrogen with oxygen
2NO

The color of nitric oxide (colorless) turns brown when it is exposed to
atmospheric because nitric oxide is oxidized to form nitrogen dioxide
when it exposed to air
...

CaC2 + N2 ∆
CaCN2 + C
CaCN2 + 3H2O
CaCO3 + 2NH3

Important nitrogen compounds
1- Ammonia gas (NH3)
Preparation ammonia gas in lab
By heating a mixture of ammonium chloride and slaked lime (Ca (OH)2)
2NH4Cl + Ca (OH) 2 ∆
CaCl2 + 2NH4OH
∆
2NH4OH
2NH3 + 2H2O
Amm
oniu
m
chlori
de +
slake
d
lime

NH3

Quick
lime
for og
Preparation
drying
ammonia
in lab

Ammonia gas is dried by passing it in quick lime
(CaO) because quick lime dose not react with
ammonia gas conc
...

Ammonia gas is collected by down – word
displacement of air because it is lighter than air or
density of NH3 is less than air
...

2- It is easily soluble in water to from NH4OH which turns the red litmus
solution into blue
...

1- Setup the apparatus as show in
figure the lower bottle contains
litmus solution
...
R
...

N2 + 3H2
2NH3
2- Nitric acid HNO3
1- Preparation of nitric acid in lab
2KNO3 + H2SO4

∆

K2SO4 + 2HNO3

The apparatus for preparation of nitric acid does not contain rubber
stopper because the vapors of nitric acid damage the organic materials as
rubber
...
dose not exceed more than 100ºC because the
acid is decomposed thermally

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