# mq2b - 1. (6 pts) In the following reaction 2 MnO4-(aq) + 5...

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235 92 U 1. (6 pts) In the following reaction 2 MnO 4 - (aq) + 5 H 2 O 2 ( R ) + 6H + (aq) 6 2 Mn 2+ (aq) + 8 H 2 O( R ) + 5 O 2 (g) the concentration of MnO 4 - dropped from 0.5684 M to 0.5522 M in 2.23 minutes. What was the average rate of formation of O 2 , in M/min, during this time interval? a) 2.14 x 10 -3 b) 1.82 x 10 -2 c) 2.09 x 10 -2 d) 6.37 x 10 -2 e) 8.50 x 10 -1 2. (5 pts) Concentration and time data is obtained for a reaction. Which of the following statements is incorrec t about the reaction? a) If R n[A] t is plotted against time and the graph gives a straight line, the reaction was first order with respect to A. b) The half-life of a first order reaction is a constant. c) When 1/[A] t is graphed against time, the slope of the line is equal to the rate constant for a second order reaction. d) The half-life of a second order reaction decreases as the concentration of the reactants decrease. e) The rate of reaction at a specific time can be determined from the slope of the line tangent to the curve at that time on a graph of concentration versus time. 3. (5 pts) The half-life of , a naturally radioactive isotope is 7.1 x 10 8 years. Radioactive decay is a first-order kinetic reaction. Calculate the rate constant for the radioactive decay of U-235. a) 4.7 x 10 8 yr -1 b) 8.0 x 10 4 yr -1 c) 19 yr -1 d) 6.5 x 10 -5 yr -1 e) 9.8 x 10 -10 yr -1 (1) The initial rate of a hypothetical reaction 3A + B 6 2C

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was measured at different concentrations of A and B. The results are summarized below: Experiment Number Initial Concentration [A] Initial Concentration [B] Initial Rate of Reaction M/s 1 1.20 M 0.50 M 1.08 x 10 -1 2 0.40 M 0.50 M 1.2 x 10 -2 3 1.20 M 1.00 M 1.08 x 10 -1 4 0.72 M 0.48 M ? Questions 4 - 6 refer to this reaction. 4. (6 pts) The rate law for the reaction is a) rate = k[A] b) rate = k[A][B] 2 c) rate = k[A][B] d) rate = k [A] 2 [B] e) rate = k[A] 2 5. (5 pts) The numerical value of the rate constant for this reaction is a) 0.0750 b) 0.0905 c) 0.150 d) 0.384 e) 0.628 6. (5 pts) The initial rate of the reaction for experiment 4 is a) 7.4 x 10 -3 M/s b) 1.7 x 10 -2 M/s c) 3.9 x 10 -2 M/s d) 4.3 x 10 -1 M/s e) 8.5 x 10 -1 M/s (2) 7. (6 pts) A reaction is second order in C. The rate constant is determined to be 2.35 x 10 -3 M -1 s -1 . The reaction flask initially contains 0.530 M of C. How much C will remain after 12.0 minutes?
a) 0.360 M b) 0.279 M c) 0.182 M d) 0.149 M e) 0.114 M 8. (5 pts) The rate constant of a reaction which is first order in A is 7.8 x 10 -2 s -1 . What is the initial rate of the reaction when the initial concentration of A is 0.0030 M?

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## This note was uploaded on 07/17/2008 for the course CHEM 122 taught by Professor Zellmer during the Winter '07 term at Ohio State.

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mq2b - 1. (6 pts) In the following reaction 2 MnO4-(aq) + 5...

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