NAME _______________________________________ Student No. ___________________________
SECTION (circle one): A01 (Briggs, 8:30 am)
A02(Codding)
A03 (Briggs, 9:30 am)
UNIVERSITY OF VICTORIA
Version
A
CHEMISTRY 102
Mid-Term Test 2,
March 12, 2010
Version
A
This test has two parts:
PART I is a multiple choice section and is worth 26 marks. The answers for the 14 questions in this
part must be coded on the optical sense form using a SOFT PENCIL.
PART II consists of written answers and is worth 24 marks. Answer these questions on this
examination paper. Answers written partially or completely in pencil cannot be re-marked.
Hand in this entire test paper AND your optical sense form (bubble sheet) at the end of the
examination period (60 minutes). The basic Sharp EL510 calculator is the only one approved
for use in Chemistry 102. A Data Sheet accompanies this test.
Marks for Written Answers
Question 1 [3]
Question 2 [5]
Question 3 [3]
Question 4 [4]
Question 5 [3]
Question 6 [6]
TOTAL (/24)
Multiple Choice (/26)
Raw Score (/50)
TOTAL MARK (%)
Chemistry 102, Mid-Term Test 2
Version A
Page 2 of 9
PART I – Multiple Choice: Select the BEST response for each question below. [Total marks = 26]
1. This is exam Version A. Mark “A” as the answer to question 1 on the optical sense form.
2.
The standard enthalpy of formation of NiSO4(s) at 25 °C is -872.9 kJ/mole. The chemical equation to
which this value applies is:
A) ½ Ni(s) + ½ S(s) + ½ O2(g) → ½ NiSO4(s)
B) Ni(s) + S(s) + 4 O(g) → NiSO4(s)
C) Ni(s) + S(s) + 2 O2(g) → NiSO4(s)
D) ½ Ni(s) + ½ S(s) + O2(g) → ½ NiSO4(s)
E) NiSO4(s) → Ni(s) + S(s) + 4 O(g).
3. Given the reactions below, compute ΔH° (in kJ) for the reaction:
H2(g) + S(rhombic) → H2S(g)
Reaction
H2S(g) + 3/2 O2(g)
S(rhombic) + O2(g)
H2(g) + ½ O2(g)
A. 562.3
4.
→ H2O(l) + SO2(g)
→ SO2(g)
→ H2O(l)
B. -1026.2 kJ
C. +1026.2
ΔH°rxn (kJ)
- 562.3
- 297.0
- 166.9
D. +98.4
E. -69.1 kJ
Calculate ΔH° (in kJ) for this reaction: C6H4(OH)2(l) + H2O2(g) → C6H4O2(l) + 2 H2O(l)
Use the information on the Data Sheet and
+177.4 kJ
C6H4(OH)2(l) → C6H4O2(l) + H2(g)
A. -258.2
B. -384.2
D. +27.7
E. -170.1
C. 71.7
5. When a liquid is in dynamic equilibrium with its vapor in a closed container at a given temperature,
indicate ALL of the following conditions that ARE TRUE:
I)
There is no transfer of molecules between liquid and vapor
II)
The vapor pressure has a unique value
III)
The opposing processes, (liquid to vapor) and (vapor to liquid), proceed at equal rates
IV)
The concentration of vapor will change as time elapses.
A. I
B. II and III
D. III and IV
E. III
C. I, and II
Chemistry 102, Mid-Term Test 2
Version A
Page 3 of 9
6. Under which of the following conditions will vaporization best occur?
A) High molecular mass, large surface area, high kinetic energy
B) high molecular energy, small surface area
C) low kinetic energy, strong intermolecular forces, large surface area
D) small surface area, low kinetic energy, low molecular mass
E) weak forces between molecules, high kinetic energy, large surface area
7. According to the phase diagram given below, which of the following statements is INCORRECT?
A) At the temperature and pressure of point 2, substance A exists as a three-phase equilibrium system.
B) At the temperature and pressure of point 3, substance Z exists as a one-phase gaseous system.
C) If the system is maintained at the temperature of point 2 while the pressure is decreased, more Z will
vaporize.
D) If liquid Z is maintained at the pressure of point 4 while the temperature is decreased to 30 °C, the
liquid will vaporize.
E) If the pressure and temperature are changed from the values at point 3 to the values at point 1,
deposition of Z will occur.
8.
Equal quantities of hydrogen and gaseous iodine at 700 K (427 °C) are placed in a reaction vessel and
allowed to reach equilibrium according to the following equation:
H2(g) + I2(g)
2 HI(g)
If the following equilibrium concentrations are measured:[H2] = [I2] = 0.021 mol L-1 and
[HI] = 0.158 mol L-1, what is the equilibrium constant for this reaction at 700K?
A. 7.5
B. 1.2
C. 360
D. 0.018
E. 57
Chemistry 102, Mid-Term Test 2
9.
Version A
Page 4 of 9
Consider the following equilibrium:
H2(g) + ½S2(g)
H2S(g)
If the equilibrium constant for this reaction at a certain temperature is KP = 1.85 x 10-2, what is the
equilibrium constant K΄P for the following reaction at the same temperature:
2 H2S(g)
2 H2(g) + S2(g)
A. 2920
B. 54.1
D. 3.70 x 10-2
C. 7.35
E. 3.44 x 10-4
10. Sulfuryl dichloride (SO2Cl2) can be prepared by the following two-step reaction sequence.
H2S(g) + 1.5 O2(g)  SO2(g) + H2O(g)
SO2(g) + Cl2(g)  SO2Cl2(g)
The reaction quotient (Qc) for the overall (sum) reaction for producing sulfuryl dichloride is:
A.
SO 2 Cl 2 
SO 2 Cl 2 
B.
SO 2 H 2 O
H 2SO 2 1.5
C.
H 2 OSO 2 Cl 2 
Cl 2 H 2SO 2 1.5
D.
SO 2 H 2 O
H 2SO 2 
E.
H 2 OSO 2 Cl 2 
Cl 2 H 2SO 2 
11. Which of the following statements about chemical reactions is/are CORRECT?
I.
II.
III.
IV.
A reaction stops when equilibrium is reached.
If one starts with a higher pressure of gaseous reactant, the equilibrium constant will be larger.
If one starts the reaction with higher concentrations of reactants, the equilibrium
concentrations of the products will be larger.
The proportions of reactants and products will be the same at equilibrium whether one starts
with pure reactants or pure products.
A. I and II
B. II and III
D. II, III and IV
E. IV only
C. III and IV
12. Which of the following substances present in a chemical reaction would NOT be included in the
equilibrium constant expression?
A. NaCl(s)
B. H2O(l)
D. C(graphite)
E. all of them
C. NH4Cl(s)
Chemistry 102, Mid-Term Test 2
Version A
Page 5 of 9
13. Which one of the following statements is INCORRECT?
A) Molecules in the liquid state have higher entropy than molecules in the gaseous state.
B) For a given substance, △Ssublimation = △Sfusion + △Svaporization
C) A nonspontaneous process will not occur unless some external energy is supplied.
D) One form of the second law of thermodynamics is: All spontaneous processes produce an increase in
the entropy of the universe.
E) Entropy is a thermodynamic property related to the degree of disorder.
14. A spontaneous process:
A) will happen quickly.
B) releases large amounts of energy.
C) produces the maximum amount of work.
D) will continue on its own once begun.
E) is reversible.
Chemistry 102, Mid-Term Test 2
Version A
Page 6 of 9
Part II written answers to questions:
Write your answers directly on this test paper. Show all your work.
Hand in the entire test paper at the end of the test period. [Total marks = 26]
3 marks
1. When baking soda is heated it decomposes according to the following reaction:
2NaHCO3(s)
Na2CO3(s)
+ CO2(g) + H2O(g)
If sufficient baking soda is placed in a container and heated to 90 °C, the total pressure in the container
when equilibrium is reached is measured to be 0.5451 atmospheres. What is the value of Kp for this
reaction? Show your work.
Ptotal = PCO2 + PH2O = 0.5451
from the stoichiometry PCO2 = PH2O = ½ (.5451) = 0.2726
KP = [PCO2][PH2O] = (0.2726)(0.2726) = 0.7431
5 marks
2.[1] a) Define surface tension? How is surface tension related to the strength of intermolecular forces?
[1] b) How does the value of surface tension vary as the strength of intermolecular forces varies?
[1] c) Define viscosity?
[1] d) How does the value of viscosity depend on molecular size and shape?
[1] c) What is/are the attractive force(s) involved in capillary action?
Chemistry 102, Mid-Term Test 2
Version A
Page 7 of 9
3 marks
3.
For this reaction: 2SO2(g) + O2(g)
2SO3(g) the equilibrium constant Kc = 4.5 at 600 °C.
An amount of SO3 gas was placed in an otherwise empty 1.0 liter reaction vessel at 600 °C. When
equilibrium was reached, the vessel was found to contain 2.0 moles of O2 gas. What amount of SO3 (in
moles) was originally placed into the reaction vessel.
4 marks
4.
A 0.90 g sample of liquid water was introduced into an evacuated 2.00 L flask, which was then sealed
and heated to 37 °C. [Vapor pressure of water at 37 °C = 0.0634 atm].
[2] a) How many moles of water vaporized?
[2] b) What percentage, by mass, of the water remained as liquid? Show your calculations.
Chemistry 102, Mid-Term Test 2
Version A
3 marks
5.
Suppose that producing a cooling curve is an
Olympic sport and you are a sportscaster for the
official Olympic radio station. A substance, XZ,
is given to a competitor at a temperature (at
point A on the curve to the right) which is
above its boiling point. The competitor has to
convert the substance to the temperature at
point E. By writing in the spaces below,
describe to the radio audience what is
happening at each segment along the graph by
stating:
What phase or phases is/are present,
what physical change is happening and
what physical constant determines either
the slope or the length of the line.
[1.5] a)Region A to B:
[1.5] c) Region D to E:
Page 8 of 9
Chemistry 102, Mid-Term Test 2
Version A
Page 9 of 9
6 marks
6.
Consider the following reaction, for which KC = 26.7 at 298 K:
CO(g) + 2H2(g)
CH3OH(g)
A reaction mixture at 298 K initially contains 1.00 M CO(g), 1.00 M H2(g), and 1.00 M CH3OH.
[1] a) Is the reaction at equilibrium? Explain how you know.
[1] b) If not, in which direction must the reaction proceed in order to reach equilibrium? (i.e. to the right or to
the left) Explain briefly how you know.
[2] c) What is the value of KP for this reaction at 298 K?
[2] d) If the equilibrium concentration of carbon monoxide is 0.641 M, what is the equilibrium concentration
of hydrogen gas (H2)?
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