from_F03_FED_key

from_F03_FED_key - Chemistry 111 KEY Page 1 out of 8 Final...

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Chemistry 111 KEY Page 1 out of 8 Final Exam D / Fall 2003 For questions 1-2 , consider the following endothermic reaction, already at equilibrium… N 2 O 4 (g) 2 NO 2 (g) 1. If we were to decrease the volume of the flask, then… a) the equilibrium constant, Kp, would decrease. b) the equilibrium constant, Kp, would increase. c) the equilibrium constant, Kp, would remain unchanged. d) there is not enough information to decide what happens to the equilibrium constant for this reaction. 2. If we were to increase the temperature of the system, then… a) the equilibrium constant, Kp, would decrease. b) the equilibrium constant, Kp, would increase. c) the equilibrium constant, Kp, would remain unchanged. d) there is not enough information to decide what happens to the equilibrium constant for this reaction. 3. Consider the following reaction at 298 K. 2 A (g) A 2 (g) This reaction has a Δ G° = + 2.50 kJ. Determine the numerical value for Kc at 298 K. a) 8.92 b) 0.999 c) 0.0408 d) 0.365 e) 1.47 × 10 -4 . We know that… Δ = - R T ln Kp. Therefore, +2,500 J = - 8.314 J/K × 298 K × ln Kp Therefore, Kp = 0.365 However, the question is asking for Kc, not Kp. Therefore, Kp = Kc × R T ( ) Δ n g 0.365 = Kc × (0.0821 × 298) -1 Kc = 8.92 .
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Chemistry 111 KEY Page 2 out of 8 Final Exam D / Fall 2003 4. The equilibrium constant, Kc, for the following reaction is 3.00 at 25°C. A (g) + B (g) C (g) + 3 D (g) In a 2.00 L flask , we place 1.0 mol of A, 1.0 mol of B, 1.0 mol of C, and 3.0 mol of D. Initially, the reaction will… a) proceed at equal rates in both directions. b) proceed more rapidly to the right. c) proceed more rapidly to the left. d) not occur in either direction. 5. Consider the following equilibrium at 75°C, for which Kp = 9.00. A (g) + B (g) 2 C (g) In a 1.00 L flask, we place gases A, B, and C at initial pressures of 0.150, 0.150, and 0.675 atm, respectively at 75°C. What is the equilibrium pressure of gas C? a) 0.765 atm b) 0.630 atm c) 0.585 atm d) 0.375 atm e) 0.525 atm Let us start with the initial conditions… A + B 2 C init: 0.150 atm 0.150 atm 0.675 atm This will allow us to calculate Q and determine the direction of the shift. Q
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This note was uploaded on 02/08/2010 for the course CHEM 111 taught by Professor Kenney during the Spring '08 term at Case Western.

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from_F03_FED_key - Chemistry 111 KEY Page 1 out of 8 Final...

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