.

NAME _______________________________________ Student No. ___________________________
SECTION (circle one): A01 (Dr. Lipson)
A02 (Dr. Briggs)
A03 (Dr. Cartwright)
UNIVERSITY OF VICTORIA
CHEMISTRY 102
Mid-Term Test 2,
March 16, 2012
Version
A
Version
A
This test has two parts:
PART I is a multiple choice section and is worth 28 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 22 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 [4]
Question 2 [7]
Question 3 [6]
Question 4 [5]
TOTAL (/22)
Multiple Choice (/28)
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 = 28]
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 below. (Rhombic sulfur is the most stable
form of sulfur.)
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
C. +1026.2
ΔH°rxn (kJ)
- 562.3
- 297.0
- 166.9
D. +98.4
E. -69.1
Using enthalpy of formation data (see Data Sheet) and the information below, calculate
Hf o for lead oxide PbO(s).
PbO(s) + CO(g) → Pb(s) + CO2(g)
A. -372.6 kJ/mol
D. +283.0 kJ/mol
B. +252.1 kJ/mol
ΔHo = -131.4 kJ
C. -151.6 kJ/mol
E. -283.0 kJ/mol
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 from the surface of a liquid be most rapid?
A) High molecular mass, large surface area, high molecular kinetic energy
B) high molecular kinetic energy, small surface area
C) low kinetic energy, strong molecular 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? (The
numbered points are the small circles.)
A) At the temperature and pressure of point 2, substance Z 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 solid substance Z will occur.
8.
Equal numbers of moles of hydrogen and gaseous iodine at 700 K 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:
2 HI(g)
H2(g) + I2(g)
If the equilibrium constant for this reaction at a certain temperature is Kc = 0.04, what is the equilibrium
constant Kc for the following reaction at the same temperature: ½H2(g) + ½I2(g)
HI(g)
B. –5.0
A. 0.0016
C. 25
D. 5.0
E. 625
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:
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 normally 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, ΔSsublimation = ΔSfusion + ΔSvaporization
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 is one that:
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.
15. An astronaut in an orbiting spaceship has spilled a few drops of her drink, and the liquid is floating
around the cabin in the ‘weightless’ environment. In what geometric shape is each droplet most likely
to be found, and why?
A. The droplets will be spherical because of their viscosity.
B. The droplets will be long ellipses because of surface tension.
C. The droplet will be spherical because of surface tension.
D. The droplets will be a variety of random shapes because of the absence of gravity.
E. The droplets will be spherical because they are not in contact with a surface.
Chemistry 102, Mid-Term Test 2
Version A
Page 6 of 9
Part II: Written Answers 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 = 22]
[4 marks]
1. When a 4.25 gram sample of solid ammonium nitrate dissolves in 60.0 g water in a standard coffeecup calorimeter, the temperature of the solution decreases from 22.0 °C to 16.9 °C. Calculate ΔH (in
kJ per mole of NH4NO3) for the solution process. Assume the specific heat of the solution is the same
as that of pure water (DATA sheet). Ignore the small heat changes in the coffee cup apparatus itself.
NH4NO3(s)  NH4+(aq) + NO3−(aq)
Chemistry 102, Mid-Term Test 2
Version A
Page 7 of 9
[7 marks]
2.
Consider the phase diagram below, which is for an unspecified substance.
(a) [1] The normal boiling point of this substance is approximately _________ Kelvins.
(b) [1] The normal melting point of this substance is approximately _________ Kelvins.
(c) [1.5]What is the physical state (phase) of the substance under each of the following conditions?
(i) T = 150 K, P = 0.15 atm State is __________________
(ii) T = 100 K, P = 0.8 atm State is ___________________
(iii) T = 300 K, P = 1.0 atm State is __________________
(d) [3.5] Using the following graphical template, sketch the heating curve for the substance that has the
above phase diagram. Consider heating one mole of substance from 100 K to 400 K, all at a constant
pressure of one atmosphere. The extra piece of information that is known is that the molar enthalpy
of vaporization for this substance is five times its molar enthalpy of fusion. (i.e. ΔHvap ≈ 5ΔHfus)
Chemistry 102, Mid-Term Test 2
Version A
Page 8 of 9
[6 marks]
3.
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 briefly 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 one starts with the concentrations given for part (a) above and allows the reaction to reach
equilibrium, the concentration of carbon monoxide (CO) is 0.641 M. What is the equilibrium
concentration of hydrogen gas (H2)?
Chemistry 102, Mid-Term Test 2
Version A
Page 9 of 9
[5 marks]
4. [3] (a) Using standard molar entropies (S°) from the DATA sheet, calculate the standard entropy of
reaction (ΔS°rxn) for the following chemical reaction.
Ca(OH)2(s)

CaO (s) + H2O (g)
[2] (b) Briefly provide two reasons that the ΔS°rxn you calculated in part (a) has the sign that it does.
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