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CHM2046 Exam 1 February 2 practice2.pdf

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Department
Chemistry
Course
CHM 2046
Professor
Christou
Semester
Spring

Description
CHM2046 Exam 1 February 2, 2006 Ticking away the moments that make up a dull day You fritter and waste the hours in an off-hand way Kicking around on a piece of ground in your home town Waiting for someone or something to show you the way. -Time Please bubble in A, B or C as the test form code at the top right of your answer sheet. VERSION 0 For this version the correct answer to each question is a. 1. Once the reaction A + B C + D reaches equilibrium, there is no net change to the concentrations of the species involved in the reaction because: a. none of these. b. the forward rate constant (k )fis equal to the backward rate constant (k ). b c. reactions in both directions have stopped and nothing further can happen. d. the forward and backward reaction rates are both zero. e. not possible to decide without K . c 2. If the equilibrium constant, K, for a reaction A B is 1.0 x 10 , which of the following is true at equilibrium? a. [A] >> [B] b. The reaction lies far to the right-hand side. c. The forward reaction rate is much greater than the backward reaction rate. d. All of the other four statements are wrong. -5 e. The K for B A is 1.0 x 10 . 3. Consider the reaction H 2g) + I (2) 2 HI (g) At a particular moment in time, [I ] i2 found to be increasing. Which of the following statements is true at that moment? a. Q c K c b. Q c K c c. Q c K c d. Q c 0 e. cannot decide without knowing K . c 4. What is K foc the following reaction? C2H 2g) + 3 H (g2 2 CH (4) 2 [CH 4] K c 3 a. [H 2 [C H 2 2 [C 2 ][2H ] 2 3 K c 2 [CH ]4 b. c. d. e. 5. At a particular temperature, 2 SO (2) 2 SO (g) + O (2) K c 1.8 x 10 -8 2 SO (g) 2 S (g) + O (g) K = 3.0 x 10 -10 2 c Use the above information to calculate the K for che reaction below at that temperature. 2 SO (2) 2 S (g) + 2 O 2g) K c ? -18 a. 5.4 x 10 b. 3.3 x 10 -2 c. impossible to determine d. 60 e. 1.7 x 10 -2 6. K c 0.10 for the reaction below at a particular temperature. 2 SO 2g) + O (g2 2 SO 3g) What is K foc the following reaction at the same temperature? SO 3g) SO 2g) + 1/2 O (g)2 a. 3.2 b. 5.0 c. 0.32 d. 10 e. impossible to determine. -2 7. What is K foc the following reaction, whose K = 3.9 p 10 at 1000 K? 2 CO (g) C (s) + CO (g) 2 a. 3.2 b. 3.9 x 10 -2 c. 26 d. 4.8 x 10 -4 e. impossible to determine. 8. At a particular temperature, the following reaction has K = 24.cOne such reaction at equilibrium has [H O]2= 1.6 M. What is the [H O ]? 2 2 2 H 2 (2) O 2g) + 2 H O2(g) a. Impossible to determine b. 0.29 M c. 160 M d. 0.64 M e. 3.2 M 9. The reaction A + 2 B C + 2 D has K =c8. At a particular moment in time, [A] = [B] = 0.2 M, [C] = 0.6 M, and [D] = 0.8 M. Which of the following statements is true? a. Q > K and the reaction is proceeding to the left. b. Q < K and the reaction is proceeding to the right. c. Q < K and the reaction is proceeding to the left. d. Q > K and the reaction is proceeding to the right. e. The reaction is at equilibrium. 10. The reaction 2 NH (g3 N 2g) + 3 H (2) has K = 9c0 at a particular temperature. At equilibrium, [H ] = 0.32 M and [N ] = 0.10 M. What is [NH ] at equilibrium? 2 2 3 -2 a. 1.9 x 10 M -4 b. 3.6 x 10 M c. 2.8 x 10 M3 -3 d. 2.6 x 10 M e. cannot be determined without the temperature. 11. 2 CO (g) + O (2) 2 CO 2g) 1.000 atm of CO and 1.000 atm of O were 2laced in a container, and the reaction allowed to reach equilibrium. At equilibrium, P = 0.81 atm. What is K ? O2 p a. 0.46 b. 0.12 c. 0.27 d. 0.02 e. impossible to determine 12. CO (2) + H (g2 CO (g) + H O2(g) 0.050 M CO and 0.100 M H were placed in a flask and allowed to reach equilibrium at a 2 2 particular temperature where K = 2c4. What is the [H ] at 2quilibrium? a. 0.061 M b. 0.011 M c. 0.039 M d. 0.094 M e. none of the other answers 13. 2 Cr2O 3s) 4 Cr (s) + 3 O 2g) At a particular temperature, a vessel containing the above reaction at equilibrium was found to contain P O2 = 0.24 atm. What is K atpthis temperature? a. 0.014 M b. 0.24 M c. 0.058 M d. 0.62 M e. impossible to determine 14. In the following reaction, which has K = 3.2cx 10 and H = +1380 kJ, 1.0 mol of each substance is introduced into a 1.0 L vessel in the presence of a catalyst and allowed to reach equilibrium at a constant temperature. 2 CO (2) + 2 H O (g2 C 2 (4) + 3 O (g)2 If neon (Ne) gas is now added to the vessel, what will happen? a. the equilibrium concentrations will stay the same. b. [CO ]2will decrease and [C H ] w2ll4increase. c. [CO ]2will increase and [C H ] 2il4 decrease. d. all concentrations will increase. e. all concentratio
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