White Station High School Name

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1 White Station High School Name Chapter 13 ʺKineticsʺ Section: A1, A2, A3 TRUE/FALSE. Write ʹTʹ if the statement is true and ʹFʹ if the statement is false. 1) The instantaneous rate of a reaction can be determined from the graph of molarity versus time at any point on the graph. T or F 2) The concentration of reactants or products at any time during the reaction can be calculated from the integrated rate law. T or F 3) The half life for a first order rate law depends on the starting concentration. T or F 4) Heterogeneous catalysts have different phases from reactants. T or F 5) Rates of reaction can be positive or negative. T or F 6) The rate limiting step in a reaction is the slowest step in the reaction sequence. T or F 7) The overall reaction order is the sum of the orders of each reactant in the rate law. T or F MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 8) are used in automotive catalytic converters. A) Enzymes B) Nonmetal oxides C) Noble gases D) Homogeneous catalysts E) Heterogeneous catalysts 8) 9) The rate law of the overall reaction 9) A + B C is rate = k[a]2. Which of the following will not increase the rate of the reaction? A) increasing the temperature of the reaction B) increasing the concentration of reactant A C) increasing the concentration of reactant B D) adding a catalyst for the reaction E) All of these will increase the rate. A 1

2 10) A catalyst can increase the rate of a reaction. A) by providing an alternative pathway with a lower activation energy B) by lowering the overall activation energy (Ea) of the reaction 10) C) by changing the value of the frequency factor (A) D) by lowering the activation energy of the reverse reaction E) All of these are ways that a catalyst might act to increase the rate of reaction. 11) Of the following, will lower the activation energy for a reaction. A) raising the temperature of the reaction B) adding a catalyst for the reaction C) increasing the concentrations of reactants D) removing products as the reaction proceeds E) increasing the pressure 11) 12) Which energy difference in the energy profile below corresponds to the activation energy for the forward reaction? 12) A) x B) y C) x - y D) x + y E) y - x 13) The primary source of the specificity of enzymes is. A) their locations within the cell B) their bonded transition metal, which is specific to the target substrate C) their delocalized electron cloud D) their shape, which relates to the lock-and-key model E) their polarity, which matches that of their specific substrate 13) 14) In general, as temperature goes up, reaction rate. A) goes up if the reaction is endothermic B) stays the same if the reaction is first order C) stays the same regardless of whether the reaction is exothermic or endothermic D) goes up if the reaction is exothermic E) goes up regardless of whether the reaction is exothermic or endothermic 14) A 2

3 15) Which one of the following is not a valid expression for the rate of the reaction below? 15) 4NH3 + 7O2 4NO2 + 6H2O A) 1 Δ[H2O] 6 Δt B) - 1 Δ[O2] 7 Δt C) - 1 Δ[NH3] 4 Δt D) 1 Δ[NO2] 4 Δt E) All of the above are valid expressions of the reaction rate. 16) The rate of a reaction depends on. A) collision energy B) collision orientation C) collision frequency D) all of the above E) none of the above 16) 17) The half-life of a first-order reaction. A) does not depend on the initial reactant concentration B) is constant C) is the time necessary for the reactant concentration to drop to half its original value D) can be calculated from the reaction rate constant E) All of the above are correct. 17) 18) One difference between first- and second-order reactions is that. A) the rate of a first-order reaction does not depend on reactant concentrations; the rate of a second-order reaction does depend on reactant concentrations B) the rate of a first-order reaction depends on reactant concentrations; the rate of a second-order reaction does not depend on reactant concentrations C) the half-life of a first-order reaction does not depend on [A]0; the half-life of a second-order reaction does depend on [A]0 18) D) a first-order reaction can be catalyzed; a second-order reaction cannot be catalyzed E) the half-life of a first-order reaction depends on [A]0; the half-life of a second-order reaction does not depend on [A]0 A 3

4 19) The elementary reaction 19) 2NO2 (g) 2NO (g) + O2 (g) is second order in NO2 and the rate constant at 501 K is M-1s-1. The reaction half-life at this temperature when [NO2] 0 = M is s. A) 126 B) 280 C) 87 D) E) ) The combustion of ethylene proceeds by the reaction 20) C2H4 (g) + 3O2 (g) 2CO2 (g) + 2H2O (g) When the rate of disappearance of O2 is 0.23 M s-1, the rate of disappearance of C2H4 is M s-1. A) 0.35 B) 0.69 C) 0.15 D) E) ) At elevated temperatures, nitrogen dioxide decomposes to nitrogen oxide and oxygen: 21) NO2 (g) NO (g) O 2 (g) The reaction is second order in NO2 with a rate constant of M-1 s-1 at 300 C. If the initial [NO2] is M, it will take s for the concentration to drop to M. A) B) C) 3.34 D) E) ) The reaction 22) 2NO2 2NO + O2 follows second-order kinetics. At 300 C, [NO2] drops from to M in 100 s. The rate constant for the reaction is M-1s-1. A) 0.54 B) C) 0.65 D) 1.2 E) 0.81 A 4

5 23) At elevated temperatures, methylisonitrile (CH3NC) isomerizes to acetonitrile (CH3CN): 23) CH3NC (g) CH3CN (g) The dependence of the rate constant on temperature is studied and the graph below is prepared from the results. The energy of activation of this reaction is kj/mol. A) B) C) D) E) ) The rate constant of a first-order process that has a half-life of 225 s is s-1. A) B) 12.5 C) D) E) ) 25) The decomposition of N2O5 in solution in carbon tetrachloride proceeds via the reaction 25) 2N2O5 (soln) 4NO2 (soln) + O2 (soln) The reaction is first order and has a rate constant of s-1 at 64 C. The rate law for the reaction is rate =. A) k [NO 2]4 [O2] [N2O5]2 B) 2k[N2O5] C) k[n2o5] D) k [N 2O5]2 [NO2]4 [O2] E) k[n2o5]2 A 5

6 26) The rate of disappearance of HBr in the gas phase reaction 26) 2HBr (g) H2 (g) + Br2 (g) is M s-1 at 150 C. The rate of reaction is M s-1. A) B) 2.63 C) D) E) ) The decomposition of N2O5 in solution in carbon tetrachloride proceeds via the reaction 27) 2N2O5 (soln) 4NO2 (soln) + O2 (soln) The reaction is first order and has a rate constant of s-1 at 64 C. If the reaction is initiated with mol in a 1.00-L vessel, how many moles remain after 151 s? A) B) C) D) 12 E) ) Which one of the following graphs shows the correct relationship between concentration and time for a reaction that is second order in [A]? 28) A) B) C) D) E) A 6

7 29) In the Arrhenius equation, 29) k = Ae-Ea/RT is the frequency factor. A) A B) k C) e D) R E) Ea 30) The isomerization of methylisonitrile to acetonitrile 30) CH3NC (g) CH3CN (g) is first order in CH3NC. The rate constant for the reaction is s-1 at 478 K. The half-life of the reaction when the initial [CH3NC] is M is s. A) B) 3.53E 105 C) D) E) ) A particular first-order reaction has a rate constant of s-1 at 25 C. What is the magnitude of k at 95 C if Ea = 55.5 kj/mol? 31) A) B) C) 576 D) E) The data in the table below were obtained for the reaction: 2 ClO2 (aq) + 2 OH- (aq) ClO3 - (aq) + ClO2 - (aq) + H2O (1) Experiment Number [ClO2] (M) [OH-] (M) Initial Rate (M/s) ) What is the order of the reaction with respect to ClO2? 32) A) 3 B) 2 C) 0 D) 1 E) 4 A 7

8 The data in the table below were obtained for the reaction: A + B P Experiment Number [A] (M) [B] (M) Initial Rate (M/s) ) The magnitude of the rate constant is. A) 2.21 B) C) 38.0 D) 42.0 E) ) The reaction A B is first order in [A]. Consider the following data. time (s) [A] (M) ) The half-life of this reaction is s. A) 4.9 B) 3.0 C) 7.1 D) 0.14 E) ) A 8

9 Answer Key Testname: EXAMKINETCSCHP13CHANG 1) FALSE 2) TRUE 3) FALSE 4) TRUE 5) FALSE 6) TRUE 7) TRUE 8) E 9) C 10) A 11) B 12) A 13) D 14) E 15) E 16) D 17) E 18) C 19) B 20) D 21) E 22) A 23) E 24) C 25) C 26) C 27) C 28) B 29) A 30) E 31) E 32) B 33) C 34) A A 9