Questions 1-3 relate to the following reaction: 1. The rate law for decomposition of N2O5(g) in the reaction above. B. is rate = k[n2o5] 2

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1 Questions 1-3 relate to the following reaction: 2N2O5(g) 4NO2(g) + O2(g) 1. The rate law for decomposition of N2O5(g) in the reaction above A. is rate = k[n2o5] B. is rate = k[n2o5] 2 C. is rate = [NO2] 4 [O2]/[N2O5] 2 D. can t be known just by inspection of the chemical equation. 2. The rate of decomposition of N2O5(g) is 2.89 (mol N2O5) L -1 s -1. What is the rate of formation of NO2? -1 A (mol NO2) L-1 s -1 B (mol NO2) L-1 s -1 C (mol NO2) L-1 s -1 D (mol NO2) L-1 s 3. If the rate law for decomposition of N2O5(g) in the reaction above is rate = D[O2]/Dt = k[n2o5] 2, then what are the units for k? -1 A. M-2 s -1 B. M-1 s C. s -1 D. k is unitless.

2 Use the following data to answer Questions 4-8: The reaction 2I - (aq) + S2O8 2- (aq) I2(aq) + 2 SO4 2- (aq) was studied at 25 C. The following results were obtained where rate = - D[S2O8 2- ]/Dt: 4. What is the order in I -? [I - ] (M) [S2O8 2- ] (M) Initial rate (M s -1 ) x x x x x 10-6 A. zero B. first C. second D. third 5. What is the order in S2O8 2-? A. zero B. first C. second D. third 6. What is the overall order? A. zero B. first C. second D. third 7. What is the rate law? A. rate = k[i - ][S2O8 2- ] B. rate = k[i - ] 2 [S2O8 2- ] C. rate = k[i - ][S2O8 2- ] 2 D. rate = k[i2][so4 2- ] 2 / [I - ] 2 [S2O8 2- ] 8. What is the rate constant for the reaction? A. 4.9 x 10-2 M -2 s -1 B. 4.9 x 10-2 M -1 s -1 C. 3.9 x 10-3 M -2 s -1 D. 3.9 x 10-3 M -1 s -1

3 9. For a first-order reaction A B, a straight line is obtained from a plot of A. 1/[A] vs t. B. ln(1/t) vs [A]. C. ln[a] vs t. D. ln(t) vs [A]. 10. The radioactive isotope 32 P decays by first order kinetics and has a half life of 14.3 days. What is the rate constant for the decay of 32 P? A day -1 B day -1 C day -1 D day How would kinetic data have been plotted to give the following linear plot revealing the activation energy? A. Temperature on the x axis; k on the y axis. B. Temperature on the x axis; ln k on the y axis. C. 1/ temperature on the x axis; k on the y axis. D. 1/ temperature on the x axis; ln k on the y axis. 12. If the overall reaction coordinate is at right, which of the following could best describe the reaction? A. Reaction is exothermic by 5 kj/mol; activation energy for forward reaction is 12 kj/mol. B. Reaction is endothermic by 5 kj/mol; activation energy for forward reaction is 12 kj/mol. C. Reaction is exothermic by 5 kj/mol; activation energy for forward reaction is 20 kj/mol. D. Reaction is endothermic by 5 kj/mol; activation energy for forward reaction is 20 kj/mol. 13. A catalyst facilitates a reaction primarily by A. increasing the activation energy for the reverse reaction. B. lowering the activation energy of the reaction. C. decreasing the temperature at which the reaction will proceed spontaneously. D. making the reaction more exothermic.

4 14. At temperatures below 500 K, the reaction CO(g) + NO2(g) CO2(g) + NO(g) follows the rate equation: rate = k[no2] 2 Which of the mechanisms below best agrees with the experimentally observed rate equation? A. A single, elementary step CO(g) + NO2(g) CO2(g) + NO(g) B. Two steps NO2 + NO2 NO3 + NO slow NO3 + CO CO2 + NO2 fast C. Two steps NO2 NO + O slow CO + O CO2 fast D. You don t have enough information to decide. Short answer questions for kinetics: 15. For a given reaction A B, the rate constant is s -1 at 25 C. How long would it take for the concentration of a reactant to go from M to M at 25 C? 16. For a given reaction A B, the rate constant is s -1 at 25 C and the activation energy is 27.2 kj/mol. What would be the rate constant at 75 C?

5 For questions 17-22: The thermal decomposition of ammonium hydrogen sulfide at 25 C has an equilibrium constant of Kc = 1.8 x 10 4 NH4SH (s) NH3 (g) + H2S (g) 17. What is the equilibrium expression for the reaction? A. K # = ['( )][( +,] ['( -,(] B. K # =. ['( ) ][( +,] C. K # = ['( -,(] ['( ) ][( +,] D. K # = [NH 3 ][H 2 S] 18. A 10.0 g sample of ammonium hydrogen sulfide is placed into a container, what is the equilibrium concentration of ammonia? A M B. 1.8 x 10-4 M C. 3.7 x 10-4 M D. 3.0 x 10-8 M 19. If the volume of the container was decreased at equilibrium, how would the reaction shift? A. More solid formed B. More gas formed C. No change D. Not enough information 20. If the NH3 was removed from the container at equilibrium, how would the reaction shift? A. More solid formed B. More gas formed C. No change D. Not enough information 21. If the temperature of the container was raised at equilibrium, how would the reaction shift? A. More solid formed B. More gas formed C. No change D. Not enough information 22. If the reaction was completed in reverse, what would be the value of Kc? A B x 10-4 C. 3.6 x 10-4 M D M 23. Which of the following statements is true about an equilibrium reaction? A. If Q > K, the reverse reaction will proceed to form more reactants. B. If Q > K, the forward reaction will proceed to form more products. C. If Q < K, the reverse reaction will proceed to form more reactants. D. If Q =, the forward reaction will proceed to form more products.

6 24. In which of the following reactions will KC = KP? A. C(s) + CO2(g) 2 CO(g) C. 2 H2O(l) H3O + (aq) + OH (aq) B. N2(g) + O2(g) 2 NO(g) D. 2 H2O(g) + 2 Cl2(g) 4 HCl(g) + O2(g) 25. If K>>1 than the reaction A. Lies to the right (more products) B. Lies to the left (more reactants) C. Has no preference (equal) D. Not enough information For questions 26-28: The decomposition of dinitrogen tetraoxide is endothermic and has a Kp = 9.8 x 10-4 at 100 C. N2O4 (g) 2 NO2 (g) 26. If the initial partial pressure of N2O4 is 0.75 atm, what is the partial pressure of NO2 at equilibrium? A atm B atm C atm D atm 27. In the above reaction, heat can be considered a A. reactant B. product C. non-factor D. not enough info 28. If the reaction is performed at 50 C you would expect products formed. A. more B. less C. no change in D. not enough info Short answer questions for equilibrium: 29. For a reaction mol CO (g) and mol H2O (g) are combined in a 1.5 L container. If the KC is 102, what mass of CO2 will be produced at equilibrium? CO (g) + H2O (g) CO2 (g) + H2 (g) 30. Consider the exothermic reaction of methane combustion. What are three different factors which could force the production of more products? CH4 (g) + 2 O2 (g) CO2 (g) + 2 H2O (g)

7 Useful Information: R = (atm L)/(mol K) = J/(mol K) 0 o C = 273 K [ A] [A] = kt + [A] o t ½ = o 2k ln[a] t = kt + ln[a] o t ½ = k 1 1 = kt + [A] t [A] o t ½ = 1 k[a] o -Ea E k = Ae RT ln k = a æ 1 ö ç + lna R è T ø K p = K c(rt) Dn