Chem1BExam2AF2010Key

Chem1BExam2AF2010Key - Chem 1B Exam 2A Name October 4, 2010...

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Chem 1B Name Lab M T(AM) T(PM) Exam 2A October 4, 2010 Instructions: For all mathematical problems, show your work. Give the basic formula (if there is one), rearrange it if necessary, plug in data with units, round properly to the correct number of significant figures, and place a box around the answer. For essay questions, be complete, but concise. Complete sentences with proper spelling and punctuation are expected. Useful information: K w = 1.0 × 10 -14 , R = 8.314 J/mol . K 1. (4 pts.) Write the equilibrium constant expression for the following reaction. Na 2 CO 3 (s) + SO 2 (g) + 1/2O 2 (g) Na 2 SO 4 (s) + CO 2 (g) K p = P CO 2 P SO 2 × (P O 2 ) 1/2 2. (10 pts.) Consider the following endothermic reaction at equilibrium: CO(NH 2 ) 2 (s) + H 2 O(g) CO 2 (g) + 2NH 3 (g) Predict the direction in which the equilibrium will shift (if any) if: (a) P NH 3 is decreased right (b) temperature is decreased left (c) part of the CO(NH 2 ) 2 (s) is removed no shift (d) the volume of the container is increased right (e) a catalyst is added no shift 3. (8 pts.) Consider the reaction: 2ICl(g) I 2 (g) + Cl 2 (g) For this reaction, K = 0.110. A 2.00 L vessel initially contains 0.500 mol ICl, 0.200 mol I 2 and 0.200 mol Cl 2 . What is the direction of reaction as this mixture reaches equilibrium? Explain your reasoning. K = [I 2 ][Cl 2 ] [ICl] 2 Q = 0.200 mol 2.00 L 0.200 mol 2.00 L 0.500 mol 2.00 L 2 = 0.160 > 0.110 Q is larger than K. The value of Q must decrease as the reaction approaches equilibrium. Therefore, the concentration of the products must decrease (the numerator gets smaller) and
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Chem1BExam2AF2010Key - Chem 1B Exam 2A Name October 4, 2010...

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