Chemistry 10th Edition by Steven S. Zumdahl, Susan A. Zumdahl , Donald J. DeCoste Test Bank

The experimental rate law for the decomposition of nitrous oxide (N2O) to N2 and O2 is Rate = k[N2O]2 . Two mechanisms are proposed: I. N2O  N2 + O N2O + O  N2 + O2 II. 2N2O N4O2 N4O2  2N2 + O2 Which of the following could be a correct mechanism? A) Mechanism I, with the first step as the rate-determining step. B) Mechanism I, with the second step as the rate-determining step as long as the first step is a fast equilibrium step. C) Mechanism II, with the second step as the rate-determining step if the first step is a fast equilibrium step. O3 O2 + O D) None of the choices (A-C) could be correct. E) At least two of the above choices (A-C) could be correct. ANS: C PTS: 1 DIF: Easy REF: 12.5 KEY: Chemistry | general chemistry | rates of reaction | reaction mechanism | the rate law and the mechanism MSC: Conceptual 105.105. If we assume the second step of the mechanism is the rate determining step and the first step is a fast equilibrium step, which of the following rate laws is predicted by this mechanism? A) rate = k[O3] B) rate = k[O3] 2 [O2] C) rate = k[O3] 2 [O2] –1 D) rate = k[O3] 2 E) none of these ANS: C PTS: 1 DIF: Moderate REF: 12.5 KEY: Chemistry | general chemistry | rates of reaction | reaction mechanism | the rate law and the mechanism MSC: Conceptual 106. Of what use is it to find a rate law for a reaction? A) We can use the rate law to directly determine coefficients in the balanced equation. B) From the rate law we can evaluate potential reaction mechanisms. C) The rate law gives us a good indication of the thermodynamic stability of the products. D) The rate law can lead us to determine the equilibrium constant for the reaction. E) None of these. ANS: B PTS: 1 DIF: Easy REF: 12.5 KEY: Chemistry | general chemistry | rates of reaction | reaction mechanism | the rate law and the mechanism MSC: Conceptual The following questions refer to the reaction 2A2 + B2  2C. The following mechanism has been proposed: step 1 (very slow) A2 + B2  R + C step 2 (slow) A2 + R  C 107. What is the molecularity of step 2? A) unimolecular B) bimolecular C) termolecular D) quadmolecular E) molecularity cannot be determined ANS: B PTS: 1 DIF: Easy REF: 12.5 KEY: Chemistry | general chemistry | rates of reaction | reaction mechanism | elementary reaction | molecularity MSC: Conceptual O3 + O  2O2 Consider the reaction 2O3(g)  3O2(g). The following mechanism is proposed: 108. Which step is rate determining? A) both steps B) step 1 C) step 2 D) a step that is intermediate to step 1 and step 2 E) none of these ANS: B PTS: 1 DIF: Easy REF: 12.5 KEY: Chemistry | general chemistry | rates of reaction | reaction mechanism | the rate law and the mechanism | rate determining step MSC: Conceptual 109. According to collision theory, the activated complex that forms in step 1 could have which of the following structures? (The dotted lines represent partial bonds.) A) B) C) D) E) ANS: B PTS: 1 DIF: Moderate REF: 12.6 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | collision theory | activated complex MSC: Conceptual 110. According to the proposed mechanism, what should the overall rate law be? A) rate = k[A2] 2 B) rate = k[A2] C) rate = k[A2][B2] D) rate = k[A2][R] E) rate = k[R]2 ANS: C PTS: 1 DIF: Easy REF: 12.5 KEY: Chemistry | general chemistry | rates of reaction | reaction mechanism | the rate law and the mechanism MSC: Conceptual Under certain conditions the reaction H2O2 + 3I– + 2H+  I3 – + 2H2O occurs by the following series of steps: Step 1. H2O2 + H+ k–1 H3O2 + Step 2. H3O2 + + I–  H2O + HOI (slow, rate constant k2) Step 3. HOI + I–  OH– + I2 (fast, rate constant k3) Step 4. OH– + H+  H2O (fast, rate constant k4) Step 5. I2 + I–  I3 – (fast, rate constant k5) 111. Which of the steps would be called the rate-determining step? A) 1 B) 2 C) 3 D) 4 E) 5 ANS: B PTS: 1 DIF: Easy REF: 12.5 KEY: Chemistry | general chemistry | rates of reaction | reaction mechanism | the rate law and the mechanism | rate determining step MSC: Conceptual 112. The rate constant k for the reaction would be given by A) k = k2 B) k = k2k3 C) k = k2K D) k = k5 E) k = Kk2k3k4k5 ANS: C PTS: 1 DIF: Easy REF: 12.5 KEY: Chemistry | general chemistry | rates of reaction | reaction mechanism | the rate law and the mechanism MSC: Conceptual 113. The rate law for the reaction would be: A) [I3]/t = k[H2O2] B) [I3]/t = k[H2O2][H+ ][I– ] C) [I3]/t = k[H2O2][H+ ] D) [I3]/t = k[H2O2][I– ] E) [I3]/t = k[H2O2][H+ ] 2 [I– ] –3 ANS: B PTS: 1 DIF: Easy REF: 12.5 KEY: Chemistry | general chemistry | rates of reaction | reaction mechanism | the rate law and the mechanism MSC: Conceptual k1 114. The reaction: 2A + B  C has the following proposed mechanism: Step 1: A + B D (fast equilibrium) Step 2: D + B  E Step 3: E + A  C + B If step 2 is the rate-determining step, then the rate of formation of C should equal: A) k[A] B) k[A]2 [B] C) k[A]2 [B]2 D) k[A][B] E) k[A][B]2 ANS: E PTS: 1 DIF: Easy REF: 12.5 KEY: Chemistry | general chemistry | rates of reaction | reaction mechanism | the rate law and the mechanism | rate determining step MSC: Conceptual 115. The reaction 2NO + O2  2NO2 obeys the rate law – = kobsd[NO]2 [O2]. Which of the following mechanisms is consistent with the experimental rate law? A) NO + NO  N2O2 (slow) N2O2 + O2  2NO2 (fast) B) NO + O2 NO3 (fast equilibrium) NO3 + NO  2NO2 (slow) C) 2NO N2O2 (fast equilibrium) N2O2  NO2 + O (slow) NO + O  NO2 (fast) D) O2 + O2  O2 + O2 (slow) O2 + NO  NO2 + O (fast) O + NO  NO2 (fast) E) none of these ANS: B PTS: 1 DIF: Easy REF: 12.5 KEY: Chemistry | general chemistry | rates of reaction | reaction mechanism | the rate law and the mechanism MSC: Conceptual 116. The rate constant k is dependent on I. the concentration of the reactant II. the nature of the reactants III. the temperature IV. the order of the reaction A) none of these B) one of these C) two of these D) three of these Y X W A B C Z E) all of these ANS: C PTS: 1 DIF: Easy REF: 12.6 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | collision theory MSC: Conceptual The questions below refer to the following diagram: Reaction Process 117. Why is this reaction considered to be exothermic? A) Because energy difference B is greater than energy difference C. B) Because energy difference B is greater than energy difference A. C) Because energy difference A is greater than energy difference C. D) Because energy difference B is greater than energy difference C plus energy difference A. E) Because energy difference A and energy difference C are about equal. ANS: B PTS: 1 DIF: Easy REF: 12.6 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | collision theory MSC: Conceptual 118. At what point on the graph is the activated complex present? A) point W B) point X C) point Y D) point Z E) none of these ANS: C PTS: 1 DIF: Easy REF: 12.6 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | collision theory | activated complex MSC: Conceptual 119. If the reaction were reversible, would the forward or the reverse reaction have a higher activation energy? A) The diagram shows no indication of any activation energy. B) The forward and reverse activation energies are equal. C) The forward activation energy would be greater. D) The reverse activation energy would be greater. E) None of these. ANS: D PTS: 1 DIF: Easy REF: 12.6 P ote ntial E n erg y a e c d b KEY: Chemistry | general chemistry | rates of reaction | reaction rate | collision theory | activation energy MSC: Conceptual 120. What would happen if the kinetic energy of the reactants was not enough to provide the needed activation energy? A) The products would be produced at a lower energy state. B) The rate of the reaction would tend to increase. C) The activated complex would convert into products. D) The reactants would continue to exist in their present form. E) The products would form at an unstable energy state. ANS: D PTS: 1 DIF: Easy REF: 12.6 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | collision theory | activation energy MSC: Conceptual 121. The rate constant for a reaction at 40.0°C is exactly 3 times that at 20.0°C. Calculate the Arrhenius energy of activation for the reaction. A) 9.13 kJ/mol B) 5.04 kJ/mol C) 41.9 kJ/mol D) 3.00 kJ/mol E) none of these ANS: C PTS: 1 DIF: Moderate REF: 12.6 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | Arrhenius equation MSC: Quantitative Use the potential energy diagram shown to answer the following: 122. Which letter shows the activation energy (without use of a catalyst)? A) a B) b C) c D) d E) e ANS: A PTS: 1 DIF: Easy REF: 12.6 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | collision theory | activation energy MSC: Conceptual 123. Which letter shows the change in energy for the overall reaction? A) a B) b C) c D) d E) e ANS: D PTS: 1 DIF: Easy REF: 12.6 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | collision theory MSC: Conceptual 124. Which letter shows the activation energy using a catalyst? A) a B) b C) c D) d E) e ANS: E PTS: 1 DIF: Easy REF: 12.7 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | collision theory | activation energy MSC: Conceptual The questions below refer to the following information: The rate constant k for the reaction shown below is 2.6  10–8 L/mol  s when the reaction proceeds at 300.0 K. The activation energy is 98000 J/mol. (The universal gas constant, R, is 8.314 J/mol·K) 2NOCl  2NO + Cl2 125. Determine the magnitude of the frequency factor for the reaction. A) 1.2  108 B) 4.6  109 C) 3.0  109 D) 2.7  108 E) 9.1  109 ANS: C PTS: 1 DIF: Moderate REF: 12.6 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | Arrhenius equation MSC: Quantitative 126. If the temperature changed to 310 K, the rate constant k would change. The ratio of k at 310 K to k at 300.0 K is closest to what whole number? A) 1 B) 2 C) 3 D) 4 E) 5 ANS: D PTS: 1 DIF: Difficult REF: 12.6 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | Arrhenius equation MSC: Quantitative 127. Use the following information to determine the activation energy for the reaction shown here: Temperature (K) Rate Constant (L/mol·s) 1400 0.143 1500 0.685 A) 6.6  104 J/mol B) 1.3  101 J/mol C) 9.4  103 J/mol D) 3.3  104 J/mol E) 2.7  105 J/mol ANS: E PTS: 1 DIF: Moderate REF: 12.6 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | Arrhenius equation MSC: Quantitative 128. When ethyl chloride, CH3CH2Cl, is dissolved in 1.0 M NaOH, it is converted into ethanol, CH3CH2OH, by the reaction: At 25°C the reaction is first order in CH3CH2Cl, and the rate constant is 3.1  10–3 s –1 . If the activation parameters are A = 3.4  1014 s –1 and Ea = 100.0 kJ/mol, what will the rate constant be at 40.°C? A) 2.1  102 s –1 B) 4.5  104 s –1 C) 2.2  103 s –1 D) 6.0  103 s –1 E) 1.6  103 s –1 ANS: A PTS: 1 DIF: Moderate REF: 12.6 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | Arrhenius equation MSC: Quantitative 129. Which of the following statements best describes the condition(s) needed for a successful formation of a product according to the collision model? A) The collision must involve a sufficient amount of energy, provided from the motion of the particles, to overcome the activation energy. B) The relative orientation of the particles has little or no effect on the formation of the product. C) The relative orientation of the particles has an effect only if the kinetic energy of the particles is below some minimum value. D) The relative orientation of the particles must allow for formation of the new bonds in the product. E) The energy of the incoming particles must be above a certain minimum value, and the relative orientation of the particles must allow for formation of new bonds in the product. ANS: E PTS: 1 DIF: Easy REF: 12.6 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | collision theory MSC: Conceptual 130. The rate constant for a reaction is 1.5  10–2 s –1 at 734 K and 3.9  10–2 s –1 at 878 K. What is the activation energy? A) 15 kJ/mol B) 36 kJ/mol C) 440 kJ/mol D) 4300 kJ/mol E) This can't be solved without knowing the frequency factor. ANS: B PTS: 1 DIF: Moderate REF: 12.6 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | Arrhenius equation MSC: Quantitative 131. For the second-order reaction NO(g) + O3(g)  NO2(g) + O2(g), the rate constant has been measured to be 1.08  107 M–1 s –1 at 298 K and the activation energy has been measured to be 11.4 kJ/mol over the temperature range 195 K to 304 K. What is the rate constant at 233 K? (R = 8.3145 J K–1 mol–1 ) A) 1.08  107 M–1 s –1 B) 1.08  109 M–1 s –1 C) 2.99  106 M–1 s –1 D) 3.90  107 M–1 s –1 E) 9.51  105 M–1 s –1 ANS: C PTS: 1 DIF: Difficult REF: 12.6 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | Arrhenius equation MSC: Quantitative 132. The reaction 2H2O2  2H2O + O2 has the following mechanism: H2O2 + I–  H2O + IO– H2O2 + IO–  H2O + O2 + I– The catalyst in the reaction is: A) H2O B) I – C) H2O2 D) IO– E) There is no catalyst in this reaction. ANS: B PTS: 1 DIF: Easy REF: 12.7 KEY: Chemistry | general chemistry | rates of reaction | reaction mechanism | catalysis MSC: Conceptual 133. Which of the following statements is typically true for a catalyst? I. The concentration of the catalyst will go down as a reaction proceeds. II. The catalyst provides a new pathway in the reaction mechanism. III. The catalyst speeds up the reaction. A) I only B) II only C) III only D) I and III E) II and III ANS: E PTS: 1 DIF: Easy REF: 12.7 KEY: Chemistry | general chemistry | rates of reaction | reaction mechanism | catalysis MSC: Conceptual 134. The catalyzed pathway in a reaction mechanism has a activation energy and thus causes a _ reaction rate. A) higher, lower B) higher, higher C) lower, higher D) lower, steady E) higher, steady ANS: C PTS: 1 DIF: Easy REF: 12.7 KEY: Chemistry | general chemistry | rates of reaction | reaction mechanism | catalysis MSC: Conceptual 135. Which of the following statements about enzymes is incorrect? A) They are proteins that catalyze specific biologic reactions. B) Several hundred are now known. C) The molecules they react with are called substrates. D) They are equal to inorganic catalysts in efficiency. E) All of these are correct. ANS: D PTS: 1 DIF: Moderate REF: 12.7 KEY: Chemistry | general chemistry | rates of reaction | reaction mechanism | catalysis | enzyme catalysis MSC: Conceptual 136. Determine (a) the rate equation and (b) the rate constant for the hypothetical reaction A + B  C given the following initial concentrations and initial rate data. [A]0 [B]0 Initial Rate Run # (mol/L) (mol/L) (mol/L·s) (1) 0.100 0.100 0.18 (2) 0.100 0.200 0.36 (3) 0.200 0.200 1.44 ANS: a) rate = k[A]2 [B] (b) 1.8  102 L 2 /mol2 s a) Use method of initial rates to solve for exponents: 4 = [2]n ; n = 2 2 = [2]m ; m = 1 Therefore the rate law is: rate = k[A]2 [B] b) To solve for k, use any set of experimental conditions in the rate law: 0.18 mol/L·s = k(0.100 mol/L)2 (0.100 mol/L) k = 0.18 mol/L·s / (0.100)3 mol3 /L3 ; k = 1.8  102 L 2 /mol2 s PTS: 1 DIF: Moderate REF: 12.3 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration MSC: Quantitative A reaction represented by the equation was studied at a specific temperature and the following data were collected: 3O2 (g)  2O3 (g) Time (seconds) Total pressure (atm) 0 1.000 46.89 0.9500 98.82 0.9033 137.9 0.8733 200.0 0.8333 286.9 0.7900 337.9 0.7700 511.3 0.7233 137. What is the rate law for this reaction? ANS: rate = k[O2] Data given represents "total pressure," so it must be adjusted to consider only . 3O2  2O3 Before 1.000 0 Change -3x +2x After 1.000 – 3x 2x Total P = 1.000 – 3x + 2x = 1.000 – x At t=46.89, P = 1.000 – x = 0.9500; x = 0.0500 Thus, PO2 = 1.000 – 3(0.0500) = 0.0850 The corrected table is: Time (seconds) Total pressure (atm) 0 1.000 46.89 0.850 98.82 0.710 137.9 0.620 200.0 0.500 286.9 0.370 337.9 0.310 511.3 0.170 This data will give a straight-line plot for versus time, indicating the reaction is first-order in O2. PTS: 1 DIF: Moderate REF: 12.4 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | graphing of kinetic data MSC: Conceptual 138. What is the value of the rate constant? ANS: k = 3.47 x 10–3 sec–1 This is the slope of the straight line resulting from graph of versus time (see answer to previous problem). PTS: 1 DIF: Moderate REF: 12.4 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | graphing of kinetic data MSC: Quantitative 139. How many seconds would it take for the total pressure to be 0.7133 atm? ANS: 567 s Total pressure of 0.7133 atm must be corrected to reflect only (see answer to #123). 1.000-x = 0.7133; x = 0.287 1.000-3(0.287) = 0.140 atm (k = 0.00347 sec–1 from previous problem) ln(0.140) = –0.00347t + ln(1.000); t = 567 s PTS: 1 DIF: Moderate REF: 12.4 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | graphing of kinetic data MSC: Quantitative For the reaction aA  Products, use the following choices a) zero order in A b) first order in A c) second order in A d) a, b, c e) none of the above 140. The half-life is constant. ANS: b For a first-order reaction, the half-life is not dependent on concentration, but it is for zero-order and second-order reactions. See Sec 12.4, Zumdahl Chemistry. PTS: 1 DIF: Easy REF: 12.4 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | half-life of a reaction MSC: Conceptual 141. A plot of [A] vs. t is a straight line. ANS: a The integrated rate law for a zero-order reaction is: [A] = -kt + [A] 0 See Sec 12.4, Zumdahl Chemistry. PTS: 1 DIF: Moderate REF: 12.4 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | graphing of kinetic data MSC: Conceptual 142. [A] is constant. ANS: e [A] is the amount of reactant at any time during the reaction. If [A] is constant then there is no reaction occurring. See Sec. 12.4, Zumdahl Chemistry. PTS: 1 DIF: Easy REF: 12.4 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws MSC: Conceptual 143. The rate is constant over time. ANS: a For a zero-order reaction, the rate law only depends on k, and not at all on the amount of reactant present, so it is constant. See Sec. 12.4, Zumdahl Chemistry. PTS: 1 DIF: Easy REF: 12.4 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws MSC: Conceptual 144. Consider the reaction, 3 A + 5 B 4 C + 7 D. If C is being produced at a rate of 2.43 mol/L s, at what rate is [A] decreasing? A) 1.82 mol/L s B) 3.24 mol/L s C) 3.6 mol/L s D) –1.82 mol/L s E) 2.43 mol/L s ANS: A PTS: 1 DIF: Easy REF: 12.1 KEY: Chemistry | general chemistry | rates of reaction | reaction rate MSC: Quantitative 145. Consider the reaction, 3 A + 5 B  4 C + 7 D. If C is being produced at a rate of 1.96 mol/L s, at what rate is [D] increasing? A) 3.43 mol/L s B) 1.12 mol/L s C) 2.1 mol/L s D) –3.43 mol/L s E) 1.96 mol/L s ANS: A PTS: 1 DIF: Easy REF: 12.1 KEY: Chemistry | general chemistry | rates of reaction | reaction rate MSC: Quantitative 146. The rate law of a particular reaction is found to be, rate = k[A] 2 [B]. Which of the following statements is FALSE? A) The reaction is third order overall. B) The units of k could be (L2 /mol2 s) C) Tripling the concentration of A will result in a nine-fold increase in the rate. D) The actual value of k will depend on the temperature E) The actual value of k will depend on the concentrations of A and B. ANS: E PTS: 1 DIF: Easy REF: 12.3 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | rate law MSC: Conceptual 147. The following data were obtained for the reaction, C + D + E  products. Determine the rate law. Initial [C] mol/L Initial [D] mol/L Initial [E] mol/L Initial rate (mol/Ls) 0.15 0.22 0.34 5.11 x 10-3 0.30 0.22 0.34 1.02 x 10-2 0.45 0.33 0.34 2.30 x 10-2 0.30 0.22 0.68 1.03 x 10-2 A) rate = k[C][D][E] B) rate = k[C]2 [D] C) rate = k[C][D] D) rate = k[C][E] E) rate = k[E][D] ANS: C PTS: 1 DIF: Easy REF: 12.3 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining rate law MSC: Conceptual 148. The following data were obtained for the reaction, C + D + E  products. Determine the value of k (do not include units) Initial [C] mol/L Initial [D] mol/L Initial [E] mol/L Initial rate (mol/Ls) 0.15 0.22 0.34 5.11 x 10-3 0.30 0.22 0.34 1.02 x 10-2 0.45 0.33 0.34 2.30 x 10-2 0.30 0.22 0.68 1.03 x 10-2 A) 0.46 B) 0.23 C) 0.15 D) 0.10 E) 0.068 ANS: C PTS: 1 DIF: Easy REF: 12.3 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining rate law MSC: Quantitative 149. The following data were obtained for the reaction, C + D + E  products. Determine the units of k. Initial [C] mol/L Initial [D] mol/L Initial [E] mol/L Initial rate (mol/Ls) 0.15 0.22 0.34 5.11 x 10-3 0.30 0.22 0.34 1.02 x 10-2 0.45 0.33 0.34 2.30 x 10-2 0.30 0.22 0.68 1.03 x 10-2 A) mol/L B) mol/L·s C) 1/s D) L/mol·s E) L 2 /mol2 ·s ANS: D PTS: 1 DIF: Easy REF: 12.3 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining rate law MSC: Conceptual 150. Determine the rate law for the reaction: C2H4Br2 + 3KI  C2H4 + 2KBr +KI3, given the initial rate data below? [C2H4Br2], M [KI], M [KI3]/t (M min-1) 0.500 1.80 0.269 0.500 7.20 1.08 1.50 1.80 0.807 A) rate = k[KI] B) rate = k[C2H4Br2] C) rate = k[KI]2 D) rate = k[KI][C2H4Br2] E) rate = k[KI][C2H4Br2] 2 ANS: D PTS: 1 DIF: Easy REF: 12.3 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining rate law MSC: Conceptual 151. Determine the value of k (without units) for the reaction: C2H4Br2 + 3KI  C2H4 + 2KBr +KI3, given the initial rate data below? [C2H4Br2], M [KI], M [KI3]/t (M min-1) 0.500 1.80 0.269 0.500 7.20 1.08 1.50 1.80 0.807 A) 0.149 B) 0.538 C) 0.0830 D) 0.299 E) 0.598 ANS: D PTS: 1 DIF: Easy REF: 12.3 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining rate law MSC: Quantitative 152. Determine the units of k for the reaction: C2H4Br2 + 3KI  C2H4 + 2KBr +KI3, given the initial rate data below? [C2H4Br2], M [KI], M [KI3]/t (M s-1) 0.500 1.80 0.269 0.500 7.20 1.08 1.50 1.80 0.807 A) mol/L B) mol/L·s C) 1/s D) L/mol·s E) L 2 /mol2 ·s ANS: D PTS: 1 DIF: Easy REF: 12.3 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | determining rate law MSC: Conceptual 153. Which statement is true about the reaction 2A B + C which is first order in A and first order overall? A) The rate of the reaction will decrease at higher concentrations of B and C. B) The time required for one half of A to react is directly proportional to the quantity of A. C) The rate of formation of C is twice the rate of reaction of A. D) The rate of formation of B is the same as the rate of reaction of A. E) The concentration of A will decrease exponentially. ANS: E PTS: 1 DIF: Easy REF: 12.3 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | dependence of rate on concentration | rate law MSC: Conceptual 154. The first-order decomposition of H2O2 at -30 C occurs with a half-life of 42.0 seconds. What will be the residual concentration of 10.2 mol/L H2O2 after 3 minutes? A) 0.326 mol/L B) 0.523 mol/L C) 8.73 mol/L D) 9.71 mol/L E) 11.9 mol/L ANS: B PTS: 1 DIF: Difficult REF: 12.4 KEY: Chemistry | general chemistry | rates of reaction | reaction rate | integrated rate laws | first-order reaction MSC: Quantitative 155. The dimerization of NO2 has a rate constant at 25 C of 2.45 x 10-2 L/mol min. What will be the concentration of NO2 after 120. seconds, given a starting concentration of NO2 of 11.5 mol/L? A) 0.331 mol/L B) 0.608 mol/L C) 7.36 mol/L D) 10.95 mol/L E) 12.1 mol/L