CHMA11H3 Final: CHMA11H3 Final Exam 2015 Practice with Solutions
1
Multiple Choice Questions (1 Mark Each, Total Marks = 50)
Your multiple choice answers MUST be transferred to the scantron DURING the time allotted for the test. ONLY THE
ANSWERS ON THE SCANTRON SHEET WILL BE SCORED.
1) Consider the following reaction, equilibrium concentrations, and equilibrium constant at a
particular temperature. Determine the equilibrium pressure of CO.
CO(g) + 2 H2(g) ⇌ CH3OH(l) Kp = 2.25 × 104
P(H2)eq = 0.52 atm
1) _______
A)
8.3 x 104 atm
B)
1.6 x 10-4 atm
C)
6.25 x 10-3 atm
D)
1.2 x 10-5 atm
E)
8.5 x 10-5 atm
2) Identify the location of oxidation in an electrochemical cell. 2) _______
A) the salt bridge
B) the anode
C) the socket
D) the cathode
E) the electrode
3) Which of the following is NOT true for ΔGrxn? 3) _______
A) IfΔG°rxn > 0, the reaction is spontaneous in the forward direction.
B) IfΔG°rxn = 0, the reaction is spontaneous in the reverse direction.
C) Under equilibrium conditions, ΔGrxn = 0.
D) If Q = 1, then Grxn = ΔG°rxn.
E) IfΔG°rxn > 0, the reaction is spontaneous in the reverse direction.
4) Use Hess's law to calculate ΔG°rxn using the following information.
NO(g) + O(g) → NO2(g) ΔG°rxn = ?
2 O3(g) → 3 O2(g) ΔG°rxn = +489.6 kJ
O2(g) → 2 O(g) ΔG°rxn = +463.4 kJ
NO(g) + O3(g) → NO2(g) + O2(g) ΔG°rxn = - 199.5 kJ
4) _______
A) +753.5 kJ B) -1152.5 kJ C) -676.0 kJ D) +277.0 kJ E) -225.7 kJ
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5) Estimate ΔG°rxn for the following reaction at 449.0 K.
CH2O(g) + 2 H2(g) → CH4(g) + H2O(g) ΔH°= -94.9 kJ; ΔS°= -224.2 J/K
5) _______
A) -101 kJ B) +2.4 kJ C) +12.9 kJ D) +5.8 kJ E) -4.2 kJ
6) Determine the value of Kc for the following reaction if the equilibrium concentrations are as
follows: [HCl]eq = 0.13 M, [HI]eq = 5.6 × 10-16 M, [Cl2]eq = 0.0019 M.
2 HCl(g) + I2(s) ⇌ 2 HI(g) + Cl2(g)
6) _______
A)
1.2 × 1017
B)
8.2 × 10-18
C)
3.5 × 10-32
D)
2.9 × 1031
E)
1.4 × 10-19
7) Identify an homogeneous catalyst. 7) _______
A) H2SO4 with concentrated HCl
B) SO2 over vanadium (V) oxide
C) N2 and H2 catalyzed by Fe
D) Pd in H2 gas
E) Pt with methane
8) Calculate the mass of oxygen (in mg) dissolved in a 5.00 L bucket of water exposed to a pressure
of 1.13 atm of air. Assume the mole fraction of oxygen in air to be 0.21 and the Henry's law
constant for oxygen in water at this temperature to be 1.3 × 10-3 M/atm.
8) _______
A) 27.3 mg B) 23.5 mg C) 13.7 mg D) 49.4 mg E) 9.87 mg
9) Calculate ΔGrxn at 298 K under the conditions shown below for the following reaction.
Fe2O3(s) + 3 CO(g) → 2 Fe(s) + 3 CO2(g) ΔG° = -28.0 kJ
P(CO) = 1.4 atm, P(CO2) = 2.1 atm
9) _______
A) +2.99 kJ B) -25.0 kJ C) +17.5 kJ D) -30.7 kJ E) +31.0 kJ
10) Calculate the cell potential for the following reaction that takes place in an electrochemical cell at
25°C.
Sn(s) ∣ Sn2+(aq, 0.022 M) Ag+(aq, 2.7 M) ∣ Ag(s)
10) ______
A) +0.01 V B) -0.66 V C) +1.01 V D) +1.31 V E) -0.83 V
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11) What statement is NOT true about standard electrode potentials? 11) ______
A) Electrons will flow from more negative electrode to more positive electrode.
B) E°cell is the difference in voltage between the anode and the cathode.
C) The electrode in any half-cell with a greater tendency to undergo reduction is positively
charged relative to the standard hydrogen electrode and therefore has a positive E°.
D)
E°cell is positive for spontaneous reactions.
E) The electrode potential of the standard hydrogen electrode is exactly zero.
12) Consider a reaction that has a positive ΔH and a positive ΔS. Which of the following statements
is TRUE?
12) ______
A) This reaction will be nonspontaneous only at high temperatures.
B) This reaction will be spontaneous only at high temperatures.
C) This reaction will be spontaneous at all temperatures.
D) This reaction will be nonspontaneous at all temperatures.
E) It is not possible to determine without more information.
13) A 1.50 L buffer solution is 0.250 M in HF and 0.250 M in NaF. Calculate the pH of the solution
after the addition of 0.0500 moles of solid NaOH. Assume no volume change upon the addition
of base. The Ka for HF is 3.5 × 10-4.
13) ______
A) 3.46 B) 3.63 C) 3.34 D) 2.89 E) 3.57
14) Determine the [OH⁻] concentration in a 0.169 M Ca(OH)2 solution. 14) ______
A) 0.298 M
B) 0.169 M
C)
2.96 × 10-14 M
D) 0.338 M
E)
5.92 × 10-14 M
15) Ethyl chloride, C2H5Cl, is used as a local anesthetic. It works by cooling tissue as it vaporizes; its
heat of vaporization is 26.4 kJ/mol. How much heat could be removed by 20.0 g of ethyl
chloride?
15) ______
A) 341 kJ B) 8.18 kJ C) 528 kJ D) 3410 kJ
16) Given the following equation,
N2O(g) + NO2(g) → 3 NO(g) ΔG°rxn = -23.0 kJ
Calculate ΔG°rxn for the following reaction.
9 NO(g) → 3N2O(g) + 3NO2(g)
16) ______
A) 69.0 kJ B) -69.0 kJ C) 23.0 kJ D) -7.67 kJ E) -23.0 kJ
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CHMA11H3 Full Course Notes
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Document Summary
Multiple choice questions (1 mark each, total marks = 50) Your multiple choice answers must be transferred to the scantron during the time allotted for the test. Answers on the scantron sheet will be scored: consider the following reaction, equilibrium concentrations, and equilibrium constant at a, _______ particular temperature. G rxn = - 199. 5 kj: +753. 5 kj, -1152. 5 kj, -676. 0 kj, +277. 0 kj, -225. 7 kj. 1: estimate g rxn for the following reaction at 449. 0 k, _______ Fe2o3(s) + 3 co(g) 2 fe(s) + 3 co 2(g) P(co) = 1. 4 atm, p(co2) = 2. 1 atm. G = -28. 0 kj: +2. 99 kj, -25. 0 kj, +17. 5 kj, -30. 7 kj, +31. 0 kj, calculate the cell potential for the following reaction that takes place in an electrochemical cell at, ______ Ag+(aq, 2. 7 m) ag(s: +0. 01 v, -0. 66 v, +1. 01 v, +1. 31 v, -0. 83 v. Calculate the ph of the solution: ______ after the addition of 0. 0500 moles of solid naoh.
