February 15, 2012Gas constant, R = 8.314 J/K  molCHEM 188 – Spring, 2012Hour Exam 1 (Early)February 15, 2012Instructions:Your scantron answer sheet must show your NAME, 7-DIGIT KU ID NUMBER, and LAB SECTION. (Begin these entries at the LEFT end of the space provided.)In answering the questions, be careful to fill in the corresponding circles on the answer sheet according to the number of the question on the exam. USE A SOFT (No. 2) PENCIL.Useful information:Gas constant, R = 8.314 J/K  mol = 0.08206 L  atm/K  mol Integrated Rate Laws: kt[A]1[A]1 :orderSeconde[A] [A] :order-Firstkt - [A] [A] :order-Zero0kt00Arrhenius equation: /RT-Ea Ae k  2121a21TTTTRE kklnRelation of KP to KC: KP = KC(RT)n Quadratic formula: aacbbx24211. Consider the reaction 2NO(g) + O2(g) 2NO2(g)Suppose that at a particular moment during the reaction oxygen (O2) is reacting at the rate of 0.025 M/s. At what rate is NO2 being formed? A. –0.050 M/s B. –0.025 M/s C. +0.025 M/s D. +0.050 M/s E. +0.10 M/s2. For the overall chemical equation, which one of the following can you rightly assume? NH4+(aq) + NO2-(aq) N2(g) + 2 H2O(l)A. The reaction is first-order overall.B. The reaction is second-order overall.C. The reaction is third-order overall.D. The rate law is, rate = k[NH4+][NO2]E. The rate law cannot be determined from the information given.3. The rate law for the reaction A + 2B  C + D is given by rate = k[A][B]. At 25°C, the rate constant is 0.25 M1s1. Calculate the rate of the reaction at this temperature if [A] = 0.50 M and [B] = 0.25 M.A. 3.9  103 M/s B. 7.8  103 M/s C. 1.6  102 M/s D. 3.1  102 M/s E. none of the above4. Consider the hypothetical reaction A + 2B  products. Use the following data to determine the rate constant, k, for the reaction. Expt. # [A]0 [B]0 Initial rate 1 0.20 0.20 0.73 M/min 2 0.20 0.40 0.73 M/min 3 0.40 0.20 1.46 M/min A. 3.8 min-1 B. 7.3 min-1C. 11 min-1 D. 22 min-1 E. 26 min-15. If concentration is expressed in units of moles per liter (mol/L) and time in units of seconds (s),the units of a second-order rate constant areA. L mol 1 s 1B. L2 mol 2 s 1 C. s  1D. s  2E. mol L 1 s 16. A certain first-order reaction A  B is 25% complete in 16 minutes at 25oC. What is the half-life of the reaction?A. 4.0 min B. 8.0 min C. 16 min D. 19 min E. 39 min27. For a certain reaction, A  products, it was found that 20 minutes were required for the concentration of A to decrease from 1.0 M to 0.50 M, and that an additional 10 minutes were required for [A] to decrease from 0.50 M to 0.25 M. What is the rate law for this reaction?A. rate = k[A]1B. rate = kC. rate = k[A]D. rate = [A]2E. cannot be determined from the information given8. The rate constant for the second-order reaction 2NO2(g)  2NO(g) + O2(g)is 0.54 M 1s 1 at 300oC. If the initial concentration of NO2 was 0.50 M, what would the concentration of NO2 be after 3.0 sec?A. 0.10 M B. 0.14 M C. 0.21 M D. 0.28 M E. 0.39 M9. A certain first-order reaction A  B is 25% complete in 8.7 min at 25oC. What the rate constant, k, for this reaction at 25oC?A. 6.8 x 10 3 min 1 B. 8.2 x 10 3 min 1C. 3.3 x 10 2 min 1 D. -3.3 x 10 2 min 1E. 11 min 110. The activation energy for the following first-order reaction is 102 kJ/mol. N2O5(g)  2 NO2(g) + ½ O2(g)The value of the rate constant (k) is 8.18 x 10 7 s 1 at 0oC. What is the value of k at 20oC?A. 8.20 x 10 7 s1 B. 4.00 x 10 6 s1C. 1.76 x 10 5 s1 D. 7.00 x 10 5 s1E. 2.55 x 10 4 s111. For a certain second-order reaction, rate constant (k) at 25oC is 0.235 M1 s1. At 50oC the rate constant is 0.959 M1s1. What is the frequency factor, A, for this reaction in units of M1s1?A. 4.26  104B. 3.21  105C. 2.41  106D. 1.82  107E. 1.37  10812. The activation energy of a certain uncatalyzed reaction is 70 kJ/mol. In the presence of a catalyst, the Ea is 60 kJ/mol. How many times faster is the catalyzed than the uncatalyzed reaction at 500oC? (Assume the frequency factor remains the same.)A. 4.7 times B. 10 times C. 23 times D. 49 times E. 106 times313. Hydrogen and nitric oxide undergo the following reaction: 2H2(g) + 2NO(g)  N2(g) + 2H2O(g)One proposed mechanism for the reaction is the following: 2NO  N2O2(fast equilibrium) N2O2 + H2  N2O + H2O (slow) N2O + H2  N2 + H2O (fast)Identify the reaction intermediate(s) in this proposed mechanism.A. NO B. N2O2 C. N2O D. N2O2 and H2E. N2O and N2O2 14. For the following reaction in aqueous solution, HF(aq) + H2O(l)  H3O+(aq) + F(aq)the correct expression for the equilibrium constant KC is …A. [H3O+][ F]/[HF][ H2O]B. [H3O+][ F]/[HF]C. [ F]/[HF][ H2O]D. [HF][ H2O]/ [H3O+][ F]E. none of the above.15. If the equilibrium constant is K1 for the reaction HBr(g)  ½ H2(g) + ½ Br2(g)Then for the reaction 2HBr(g)  H2(g) + Br2(g)the equilibrium constant K2 must be equal to:A. K2 = 2K1B. K2 = K12C. K2 = 1/K1 D. K2 = 1/(2K1) E. K2 = 1/K1216. The equilibrium constant KC for the reaction 2SO3(g)  2SO2(g) + O2(g) is 3.5 x 10  7 at 350oC. What is the value of KP for this reaction at 350oC?A. 6.8 x 10  9B. 1.2 x 10  8C. 3.5 x 10  7 D. 1.0 x 10  5 E. 1.8 x 10  517. The equilibrium constant Kc for the decomposition of phosgene, COCl2, is 4.63 10-3 at 527°C. 4COCl2(g)  CO(g) + Cl2(g)If, in a reaction mixture at 527°C, the concentrations of COCl2, CO, and Cl2 are 0.25 M, 0.050 M, and 0.050 M, respectively, then which one of the following statements is true?A. The system is at equilibrium; no change will occur.B. The concentrations of CO and Cl2 will increase as the system approaches equilibrium.C. The concentration of COCl2 will fall as the system approaches equilibrium.D. The concentrations of CO and Cl2 will fall as the system approaches equilibrium.E. None of the above.18. For the reaction below 2NOCl(g)  2NO(g) + Cl2(g) the equilibrium