Answer Key Mid-term 2 Version B 2-27-08

Answer Key Mid-term 2 Version B 2-27-08 - Answer Key...

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1 Answer Key Chemistry 1B, Mid-Term Exam 2, Feb 27, 2008 This is Version B of the Exam – Mark Your Scan Tron as Test Form B Questions 1-4 . A voltaic cell consists of a standard hydrogen electrode and a Pt electrode dipped in a solution containing 0.10 M Fe 3+ (aq) and 1.0 M Fe 2+ . 1. The half reaction that occurs at the anode of this cell is written as A. H 2 (g, 1 atm) 2 H + (1.0 M) + 2e - Answer B. 2 H + (1.0 M) + 2e - H 2 (g, 1 atm) C. Pt (s) + Fe 3+ (0.10 M) Pt + (aq) + Fe 2+ (1.0 M) D. Fe 2+ (1.0 M) Fe 3+ (0.10M) + e - E. Fe 3+ (0.10 M) + e - Fe 2+ (1.0 M) 2. The potential of this galvanic cell is A. 0.77 V B. greater than 0.77 V C. less than 0.77 V Answer D. negative E. 0 V 3. When this cell is connected to an external circuit and its output is used to drive a fan motor, the following will occur A. Platinum will be reduced B. Hydrogen gas will be formed C. Platinum will be oxidized D. Iron metal will plate out at the cathode E. The [H + ] at the hydrogen electrode will increase Answer 4. What happens to the cell potential if the [H + ] is increased from 1.0 M to 5.0 M? A. The potential will drop to 0 B. The potential will decrease but remain greater than 0 Answer C. The potential will increase D. The potential will become negative E. There will be no change in the potential but the free energy for the cell reaction will change. 5. Consider the reaction and reaction rate equation given below. Cl 2 ( g ) + CHCl 3 ( g ) HCl( g ) + CCl 4 ( g ) Rate = k[Cl 2 ] 1/2 [CHCl 3 ] What are the units for k, assuming time in seconds? A. L 2 / (mol 1/2 s) B. L 1/2 / (mol 2 s) C. L / (mol 1/2 s) D. L 1/2 / (mol 1/2 s) Answer E. None of the above
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2 Questions 6 and 7 . The following reaction was studied at -10°C and the results are shown in the table below
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Answer Key Mid-term 2 Version B 2-27-08 - Answer Key...

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