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CHEM LAB FINAL EXAM QUESTIONS
AND ANSWERS LATEST UPDATE
GRADED A+ 2023/2024

Which statement is true about a chemical reaction at equilibrium? - ANSWER- The
forward reaction rate is equal to the reverse reaction rate
...
If you create an equilibrium mixture from
Fe3+ and SCN− ions, adding Cl− ions will _____________________ because
______________________________
...
- ANSWER- endothermic

Heat is a product in the reaction - ANSWER- exothermic

When any reversible reaction is at equilibrium, what conditions are necessarily
true? - ANSWER- -Reactants and products are both present in the reaction mixture
...


-The amounts of reactants and products has stopped changing
...
Heat applied to an endothermic
reaction will shift the reaction towards _______________
...
- ANSWER- -titrant volume

-pH

If a 1
...
40 mL of 0
...
36 M
1
...
258 M x (32
...
0083592
2
...
0083592x1000

If 0
...
50 mL of 0
...
find moles of base:
(
...
5)/1000=
...
find molar mass of acid:

...
0011475=65

The pKa of an acid can be determined through _____________ with a strong base
...
The pKa of the acid is equal to the pH at the
___________________
...
- ANSWER- Cl-=HCl

I-=HI
SO42-=Bisulfate ion
F-=HF
OH-=Water

Given the pKa of each acid, determine whether it is strong or weak
...
1
weak

acetic acid, pKa=4
...
Rinse the pH meter with __________________
and gently pat dry
...
- ANSWER- -storage solution

-deionized water
-stabilizes

Would the pH at the equivalence point be acidic, basic, or neutral for each given
titration? - ANSWER- HClO4 with
Ba(OH)
neutral

HCl with NH3
acidic

CH3CH2OH with Sr(OH)2
basic

The equivalence point of any acid-base titration can be determined visually from a
titration curve by finding the place where - ANSWER- the curve has the steepest
slope
...


If the pH at the half-titration point of a weak acid is 4
...
3E-5

10^-4
...
0 mL sample of a saturated
Ca(OH)2 solution is titrated with 0
...
9 mL of titrant are dispensed
...
019

(
...
9)/1000
HCl is 2x the moles of Ca(OH)2
...
0 mL sample of a saturated
Ca(OH)2 solution is titrated with 0
...
5 mL of titrant are dispensed
...
034

Begin by finding the number of moles of the titrant,
HCl
...


(0
...
5)/1000

The molar solubility of
Ca(OH)2 was experimentally determined to be 0
...
Based on this value, what
is the Ksp of Ca(OH)2? - ANSWER- 0
...
022)(2*0
...
This is
because the NaF solution contains __________________ that __________ further
dissociation of PbF2 into Pb2+ and F-
...
Any further addition of salt will remain undissolved
...
- ANSWER- Solubility product
constant

A decrease in the solubility of an ionic compound as a result of the addition of a
common ion
...
ANSWER- Molar solubility
The mass of a salt in grams that will dissolve in 100 mL of water
...
25 x 10-5 M Ag+
ions
...
- ANSWER- 1
...
25E-5M)(1
...
60 mL
of 0
...
Based on this titration, what is the Ksp of AgOH?
- ANSWER- 2
...
00260 L x 0
...
54E-5/
...
41E-4
(1
...
00E-8

Consider the equilibrium describing the endothermic dissolution of a solid in
water
...

Suppose you add 0
...
0 mL of water
...
0159 M and the concentration of Cl−(aq)) is
0
...
What is the value of the equilibrium constant, Kc, for the dissolution of
PbCl2? - ANSWER- 1
...
0159 M][0
...
ANSWER- -A: 0
...
At the beginning of the titration, you read the base titrant volume as 2
...

After running the titration and reaching the endpoint, you read the base titrant
volume as 18
...

What volume, in mL, of base was required for the titration? - ANSWER- 16
...
- ANSWER- -Close to
the calculated endpoint of a titration: Partially open

-Filling the buret with titrant: completely closed

-at the beginning of aa titration: completely open

-Conditioning the buret with titrant: completely closed

A reagent added to the analyte solution that changes color when the reaction is
complete - ANSWER- Indicator

Solution of an unknown concentration that has another solution slowly added to it ANSWER- Analyte

Glassware that allows a solution to be precisely and slowly added to another
solution - ANSWER- Buret

Solution of known concentration that is slowly added to a solution of unknown
concentration - ANSWER- Titrant

Process of slowly adding a solution to react with another solution and determine
the concentration of one of the solutions based on the reaction between them ANSWER- Titration

When the required amount of one solution has been added to the second solution to
complete the reaction - ANSWER- Endpoint
How should you prepare a buret for titration before loading it with titrant? ANSWER- Condition the buret with titrant solution

Suppose you analyze a 33
...
08 g
of sodium hypochlorite present
...
14

2
...
9 x 100%

Suppose in an experiment to determine the amount of sodium hypochlorite in
bleach,
0
...
63 mL1
...
00644

mols thiosulfate= moles KIO3x6
=9
...
01463) =
...
45 mL sample of 0
...
The endpoint was observed to occur at 14
...


How many moles of
KIO3 were titrated? - ANSWER-
...
0100molx
...
0000443 mol KIO3 were titrated with an unknown solution of Na2S2O3 and the
endpoint was reached after 17
...


How many moles of
Na2S2O3 did this require? - ANSWER-
...
0000443x6

When determining the amount of an oxidant present by titration, you can use
iodine and starch as an indicator
...
When starch
and iodine are both present, the solution is ____________
...
When the
iodine has completely reacted at the endpoint of the titration, the solution should
become __________
...
- ANSWER- -water
-carbon dioxide
Identify the safety equipment designed to deal with each emergency listed
...
29 g of a fuel causes the water in a calorimeter to increase by 11
...
If
the calorimeter has a heat capacity of 3
...
8

-3
...
2=-34
...
608/1
...
8

Suppose you need to calibrate a calorimeter
...
736 g of a fuel with an enthalpy of combustion of −48
...
If the temperature
of water in the calorimeter increases by 14
...
47

-48
...
736g=-35
...
84/14
...
47=2
...

The calorimeter is __________ to prevent transfer of heat to outside the device
...
3 kJ/g and fuel B has an energy density of −35
...


The fuel with greater energy density is_________ because you need to burn
_______ of Fuel A than Fuel B to produce the same amount of heat
...

-Inform the instructor and everyone working around the area about the spill
...
- ANSWER- -The burner should be lit for 20
seconds after any change before proceeding
...

-The burner wick should be about a few millimeters above the metal stem
...

C7H16+ 11O2-----> 7CO2+ 8H2O
Using the given enthalpies of formation, ΔH∘f for each species, determine the
enthalpy of combustion of heptane
...

EoCell= 1
...
120 M solution of
Zn2+(aq) and 0
...
6 K? - ANSWER- 1
...
1032V-(8
...
6K)/(2x95485)xln(2
...
1550)

Consider the diagram of the electrochemical cell
...
The purpose of the
Na2SO4 is to ____________________
...
In the salt bridge, _________ move toward the anode and
_________ move toward the cathode
...
- ANSWER- Pressure of
1 atm
solution concentrations of 1 M
Temperature of 298 K

what is the standard cell potential - ANSWER- 1
...
36-(-
...
314 J/molK
temperature in K
number of electrons
Faraday constant
reaction quotient

The electrode where oxidation occurs

An electrochemical cell powered by a spontaneous redox reaction

An electrochemical cell that takes in energy to carry out a nonspontaneous redox
reaction

The electrode where reduction occurs

A chemical equation showing either oxidation or reduction - ANSWER- anode

galvanic cell

electrolytic cell

cathode

half-reaction

Identify the oxidation half reaction of Zn(s)
...
- ANSWER2Fe(s) + 3Cl2(g)→ 2Fe3+(aq) + 6Cl-(aq)

Al---->Al3+
Cu2+----> Cu+
2F- ----> F2 - ANSWER- oxidation, 3, product
reduction, 1, reactant
oxidation, 2, product

suppose you mix an unknown solid with oil and the added solid dissolves into the
oil
...
What is most likely true
about the unknown liquid? - ANSWER- It is a polar liquid

Determine whether the structure is correct and justify your decision - ANSWERThis solution is incorrect because the octet rule in not fulfilled
...
o-c-o

what characteristics of molecule determine whether or not it is polar? - ANSWERThe arrangement of bonds around the molecule
...


Determine whether the structure is correct and justify your decision
...
o has 2
lone pairs and 2 bonded pairs
...
ANSWER- c+o2=co2 (combustion)
CO2+4H2=CH4+2H20 (not combustion)
2NO+O2=2NO2 (combustion)
2N2O5=4NO2+O2 (not combustion)
2C2H6+7O2=4CO2+6H20 (combustion)

Determine each type of reaction - ANSWER2C2H2(G)+5O2(G)=4CO2(G)+2H2O(l): COMBUSTION

Determine each type of reaction - ANSWERCACL2(AQ)+NA2CO3(AQ)=2NACL(AQ)+CACO3(S): DOUBLE
REPLACEMENT
Determine each type of reaction - ANSWER2FE(S)+6HCL(AQ)=2FECL3(AQ)+3H2(G): SINGLE REPLACEMENT

Determine each type of reaction - ANSWER- CO(G)+2H2(G)=CH3OH(L) :
COMBINATION

Determine each type of reaction - ANSWER- NH4NO3(S)=N2O(G)+2H2O(L):
DECOMPOSITION
In the context of a balanced chemical equation, a - ANSWER- (subscript) is a
number to the lower right of an element or ion within formula and it applies to
(only the part of the formula it follows)
...
Only (coefficients) should
be added or changed when balancing chemical equations
...
At least
one reactant
...


Determine what type of reaction each unbalanced chemical equation represents
...
ANSWER- AgNO3+NaCl=NaNO3+AgCl (double replacement)

Determine what type of reaction each unbalanced chemical equation represents
...
ANSWER- CaCL2+Na3PO4=Ca3(PO4)2+NaCl (double replacement)

predict the products of hydrochloric acid reacting with zinc metal
...
6ml of a 0
...
What
mass of NaCL do you need to use to make the solution? - ANSWER- 3
...
30 g/mol
...
8 mL aqueous solution prepared with 78
...
01

Suppose you have 450
...
350 M sodium hydroxide solution
...
158

Determine whether each of the given characteristics refers to electrolytes or nonelectrolytes
...
- ANSWER- do not dissociate in solution- non-electrolytes

Determine whether each of the given characteristics refers to electrolytes or nonelectrolytes
...
- ANSWER- do not conduct electricity- non-electrolytes

Determine whether each of the given characteristics refers to electrolytes or nonelectrolytes
...
- ANSWER- examples incude NaOH and KBr- electrolytes

Determine whether each statement describes a solution of a strong electrolyte,
weak electrolyte, or non-electrolyte
...
- ANSWER- contains a completely
dissociated solute- strong electrolyte

Determine whether each statement describes a solution of a strong electrolyte,
weak electrolyte, or non-electrolyte
...
- ANSWER- contains a complete solutenonelectrolyte

Determine whether each statement describes a solution of a strong electrolyte,
weak electrolyte, or non-electrolyte
...
- ANSWER- contains a partially dissociated
solute- weak electrolyte

Calculate the percent by mass of a solution made from 19 g NaCl (the solute) and
64 g water
...
3 mL47
...
65 M HCl
solution? - ANSWER- 0
...


Use this object to fill the pipet such that the - ANSWER- (meniscus) of the liquid
is even with the volume line
...
- ANSWER-

When sodium chloride,
NaCl
, dissolves in water, the solution contains - ANSWER- (sodium ions and chloride
ions) in addition to the water solvent
...
- ANSWER- Used for applications in which great accuracy is
needed (volumetric)

Determine whether each of the properties described applies to volumetric or
graduated glassware
...
- ANSWER- Designed to measure one specific volume of
liquid (volumetric)

Identify the color flame each element that produces in a flame test - ANSWER- kfleeting lavendar flame

Identify the color flame each element that produces in a flame test - ANSWER- nabrilliant yellow flame

Suppose that you are performing a flame test with multiple solutions
...
Then, you test a calcium compound,
which should produce a brick red flame
...

For each incorrect flame appearance, select the most likely error responsible and
the necessary action to address it
...
- ANSWER- There is a
sodium impurity somewhere
...


Incorrect appearance 2: The flame remains blue
...
Dip it back in the solution and try again
...
- ANSWER- There is some of
the previous metal left on the wire
...

What visible signs indicate a precipitation reaction when two solutions are mixed?
- ANSWER- A hazy or cloudy appearance
...
- ANSWER- Cu2+, Ag+,NH+4,Bi3+

Na+, K+, and NH4+ - ANSWER- produces soluble salts of these ions

Na+ and K+ - ANSWER- these ions can be tested using the flame test

Cu2+ and Bi3+ - ANSWER- sulfide salts of these ions are considered insoluble

NH4+ - ANSWER- this ion tested when the ph increases and releases as a gas

Ag+ - ANSWER- the chloride salt is insoluble

NH4+ - ANSWER- ammonium ion

Na2Sn(OH)4 - ANSWER- sodium stannite
OH− - ANSWER- hydroxide ion

S2- - ANSWER- sulfide ion

K4[Fe(CN)6] - ANSWER- potassium hexacyanoferrate

NH3 - ANSWER- ammonia

the ammonium ion is a - ANSWER- weak acid

occurs when potassium hexacyanoferrate(II), K4[Fe(CN)6], is added to a solution
containing copper Bi3+ and Cu2+ cations
...
- ANSWER- Formation of a soluble deep blue [Cu(NH3)4]2+

When aqueous ammonia is added to a solution containing Bi3+ and Cu2+ cations ANSWER- Precipitation of white bismuth hydroxide

When hydrochloric acid is added to a solution containing Ag+ ions, - ANSWERAgCl precipitates

Addition of sodium stannite solution, Na2Sn(OH)4 to white bismuth hydroxide,
Bi(OH)3, results in - ANSWER- Reduction to black bismuth metal
Which statement is true about a chemical reaction at equilibrium? - ANSWER- The
forward reaction rate is equal to the reverse reaction rate

Identify the correct equation for the equilibrium constant Kc for the reaction given
...

A+2B=2C+D - ANSWER- C^2D/AB^2
Consider the two reactions of iron ions, one with thiocyanate and one with chloride
ions - ANSWER- If you create an equilibrium mixture from Fe3+ and SCN- ions
adding CL- ions will shift the iron equilibrium to the reactant side because it
removes iron from the iron mixture
...
The amounts of reactants and products has stopped changing
...


According to Le Châtelier's Principle, heat applied to an exothermic reaction will
shift the reaction towards - ANSWER- the reactants

Heat applied to an endothermic reaction will shift the reaction towards ANSWER- the products

The equilibria studied in the lab procedure include which two reactants? ANSWER- [CoCl4]2- and Fe3+

When using acids and bases, note that these substances are - ANSWER- corrosive

Make every effort to avoid contact with - ANSWER- the skin and lab surfaces

Be sure to wipe up any spills - ANSWER- immediately

HNO2 - ANSWER- acid
KOH - ANSWER- base

Ba(OH)2 - ANSWER- base

RbOH - ANSWER- base

HClO4 - ANSWER- acid

A neutralization reaction is a reaction between - ANSWER- an acid and a base

that results in the formation of - ANSWER- water and salt

Predict the products of hydrobromic acid,
HBr reacting with magnesium hydroxide - ANSWER- MgBr2 and H2O

In the titration setup in lab, the buret will be filled with - ANSWER- base

During the titration, a beaker placed underneath will contain - ANSWER- acid and
indicator

What is the correct reading of the volume in the pictured buret? - ANSWER- 39
...
0 x 10-3
mol
...
0 x 10-3/2 = 1
...
Determine the solubility constant Ksp, for lead iodide (quiz 9) - ANSWERKsp= (Pb 2+)[I-]2=
(1
...
003)=1
...
What is the formula of
muriatic acid? Does the ph of the swimming pool increase or decrease as a result of
adding muriatic acid? Explain
...
The pH of
the swimming pool decreases due to the dissociation of HCl
...
What is the formula
of sulfuric acid? (quiz 8) - ANSWER- H2SO4

Milk of magnesia is used as a laxative and to treat upset stomachs
...
What is the anhydrous form of washing soda? Does it increase or

decrease the pH of the wash water? Explain
...
It will
increase the pH of wash water to make the wash water make more basic
...
2 M K4Fe(CN)6

identify the reagent that separates Fe3+ from Ni2+
...
(quiz 6) - ANSWER- NH3
...
explain the chemistry of the
separation (quiz 6) - ANSWER- NaOH
...
Fe3+
becomes a precipitate
...
Stop time occurs when the solution
changes color
...
(quiz 3) ANSWER- deionized water = deionized water acts as a solvent
buffer solution (acetic acid, sodium acetate mixture) = the buffer solution
maintains the pH of the solution
...

Write a balanced equation for its reaction with hydrochloric acid
...
A
...
The mass of a gas is elusive
...
The
temperature of the gas is determined by finding the temperature of the water
...
We calculate the final mass by determining the mass of the sample before the
reaction and the final mass of the sample
...
(quiz 5) - ANSWER- CaCO3 (s) + 2 HCl (aq) yields CaCl2 (aq) +
H2O (l) + CO2 (g)

Identify the two most common anions present in antacids
...
8
g/mol) = 0
...
0992 = 0
...
00 ml aliquot of 0
...
0 ml with 0
...
1 M HNO3
...
How many moles of SCN- are present
B
...
# of moles x (volume/1000) =
0
...
003 = 3
...
3
...
2 x 10-4

What is the endpoint of a titration? - ANSWER- When the amount of acid and base
are equal

The indicator phenolphthalein is added to the _____________
...
- ANSWER- Stoichiometric
point (Ma=Mb)

Hydrochloric acid and sodium hydroxide react to form _____________
...
(titrations) ANSWER- Titrant

The reaction between sodium hydroxide and hydrochloric acid is considered which
type? - ANSWER- Neutralization

What color is phenolphthalein when the solution is acidic? - ANSWER- Colorless

Phenolphthalein is a pH indicator that is colorless in acidic solution and pink in
basic solution
...
- ANSWER- A primary standard

The concentration and volume of KHP is known

When a known quantity of compound, at a known concentration, is added to a
known volume of another compound to determine the concentration of the latter,
the process is referred to as _____________
...


If you plot the absorbance measurements of solutions vs
...
26 at 542 nm?

y=15200x-0
...
26=15200x-0
...
83x10^5

The molar absorptivity of a compound at 500 nm wavelength is 252 M-1cm-1
...
00140 moles of a solute in enough
water to make a 500
...
What would be the absorbance in a 3
...
21168

To run a spectrophotometry experiment, begin by
____ the spectrophotometer and preparing the samples
...
Once data is collected, turn off the instrument, clean the area, and
discard the samples
...
- ANSWER- Turn
on the light source and the spectrophotometer
...

Blue=
Red=
Orange=
Green= - ANSWER- Blue=Orange
Red=Green
Orange=Blue
Green=Red
What type of plot can be used to determine λmax of a solution? - ANSWERAbsorbance vs
...


CuCl2
Cu2O3
Cu2O
CaO
CaCl2 - ANSWER- CuCl2= Copper(II) chloride

Cu2O3= Copper(III) oxide
Cu2O= Copper(I) oxide
CaO= Calcium oxide
CaCl2= Calcium chloride

What is the correct formula for manganese(II) fluoride? - ANSWER- MnF2

In the reaction of magnesium metal with hydrochloric acid, how do you determine
when the magnesium metal has reacted completely? - ANSWER- Gas bubbles are
no longer produced
...


A balloon is inflated outside on a cool morning
...
As the temperature cools down again in the evening, the volume of the
balloon will ____
...
Predict the effect of each
change
...
What will happen to
the volume?

The pressure and volume are increased
...
What will
happen to the volume?

The volume and temperature remain constant, while some of the gas is let out of
the container
...

If the pressure in the eudiometer is 760
...
8 torr, what is the pressure (torr) of the H2
gas? - ANSWER- Ptotal= PH2O + PH2

736
...

After the experiment is finished, the resulting value of R would be - ANSWERToo large

An air bubble trapped in the eudiometer would affect the volume
...

In the Ideal Gas Law lab, how is the temperature of the hydrogen gas determined?
- ANSWER- The temperature of the water bath is measured after the reaction,
which is assumed to be the same temperature as the gas
...
- ANSWER- -inverse
-increases

The temperature of a room is 19
...
What is this temperature expressed in Kelvin
(K)? - ANSWER- C + 273

292
...
08206



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