Test Química Cinética Brown

A burning splint will burn more vigorously in pure oxygen than in air because. oxygen is a reactant in combustion and concentration of oxygen is higher in pure oxygen than is in air. oxygen is a catalyst for combustion. oxygen is a product of combustion. nitrogen is a product of combustion and the system reaches equilibrium at a lower temperature. nitrogen is a reactant in combustion and its low concentration in pure oxygen catalyzes the combustion.

2) Of the following, all are valid units for a reaction rate except __________. A) mol/L. B) M/s. C) mol/hr. D) g/s. E) mol/L-hr.

3) Nitrogen dioxide decomposes to nitric oxide and oxygen via the reaction: 2NO2 → 2NO + O2 In a particular experiment at 300 °C, [NO2] drops from 0.0100 to 0.00650 M in 100 s. The rate of disappearance of NO2 for this period is __________ M/s. A) 0.35. B) 3.5 × 10-3. C) 3.5 × 10-5. D) 7.0 × 10-3. E) 1.8 × 10-3.

4) At elevated temperatures, dinitrogen pentoxide decomposes to nitrogen dioxide and oxygen: 2N2O5(g) → 4NO2 (g) + O2 (g) When the rate of formation of O2 is 2.2 × 10-4 M/s, the rate of decomposition of N2O5 is __________ M/s. A) 1.1 × 10-4. B) 2.2 × 10-4. C) 2.8 × 10-4. D) 4.4 × 10-4. E) 5.5 × 10-4.

5) Which one of the following is not a valid expression for the rate of the reaction below? 4NH3 + 7O2 → 4NO2 + 6H2O. A) -1/7 Δ[O_2 ]/"Δt". B) 1/4 Δ["N" "O" _2 ]/"Δt". C) 1/6 Δ[H_2 O]/"Δt". D) -1/4 Δ["N" "H" _3 ]/"Δt". E) All of the above are valid expressions of the reaction rate.

6) Of the units below, __________ are appropriate for a first-order reaction rate constant. A) M s-1. B) s-1. C) mol/L. D) M-1 s-1. E) L mol-1 s-1.

7) The rate law of a reaction is rate = k[D][X]. The units of the rate constant are __________. A) mol L-1s-1. B) L mol-1s-1. C) mol2 L-2s-1. D) mol L-1s-2. E) L2 mol -2s-1.

The data in the table below were obtained for the reaction: A + B → P 8) The rate law for this reaction is rate = __________. A) k[A][B]. B) k[P]. C) k[A]2[B]. D) k[A]2[B]2. E) k[A]2.

9) The magnitude of the rate constant is __________. A) 38.0. B) 0.278. C) 13.2. D) 42.0. E) 2.21.

10) What is the order of the reaction with respect to ClO2?. A) 1. B) 0. C) 2. D) 3. E) 4.

11) What is the order of the reaction with respect to OH-?. A) 0. B) 1. C) 2. D) 3. E) 4.

12) What is the overall order of the reaction?. A) 4. B) 0. C) 1. D) 2. E) 3.

13) What is the magnitude of the rate constant for the reaction?. A) 1.15 × 104. B) 4.6. C) 230. D) 115. E) 713.

14) The rate law for a reaction is rate = k [A][B]2 Which one of the following statements is false?. A) The reaction is first order in A. B) The reaction is second order in B. C) The reaction is second order overall. D) k is the reaction rate constant. E) If [B] is doubled, the reaction rate will increase by a factor of 4.

15) Under constant conditions, the half-life of a first-order reaction __________. A) is the time necessary for the reactant concentration to drop to half its original value. B) is constant. C) can be calculated from the reaction rate constant. D) does not depend on the initial reactant concentration. E) All of the above are correct.

16) The reaction 2NO2 → 2NO + O2 follows second-order kinetics. At 300°C, [NO2] drops from 0.0100 M to 0.00650 M in 100.0 s. The rate constant for the reaction is __________ M-1s-1. A) 0.096. B) 0.65. C) 0.81. D) 1.2. E) 0.54.

17) The reaction CH3-N≡C → CH3-C≡N is a first-order reaction. At 230.3 °C, k = 6.29 × 10-4s-1. If [CH3NC] is 1.00 × 10-3 initially, [CH3NC] is __________ after 1.000 × 103 s. A) 5.33 × 10-4. B) 2.34 × 10-4. C) 1.88 × 10-3. D) 4.27 × 10-3. E) 1.00 × 10-6.

18) A compound decomposes by a first-order process. If 25.0% of the compound decomposes in 60.0 minutes, the half-life of the compound is __________. A) 65 minutes. B) 120 minutes. C) 145 minutes. D) 180 minutes. E) 198 minutes.

19) A compound decomposes by a first-order process. If 17.0% of the compound decomposes in 60.0 minutes, the half-life of the compound is __________. A) 141 minutes. B) 181 minutes. C) 198 minutes. D) 223 minutes. E) 325 minutes.

21) The following reaction is second order in [A] and the rate constant is 0.039 M-1s-1: A → B The concentration of A was 0.30 M at 23 s. The initial concentration of A was __________ M. A) 2.4. B) 0.27. C) 0.41. D) 3.7. E) 1.2 × 10-2.

22) The following reaction is second order in [A] and the rate constant is 0.025 M-1s-1: A → B The concentration of A was 0.65 M at 33 s. The initial concentration of A was __________ M. A) 2.4. B) 0.27. C) 0.24. D) 1.4. E) 1.2 × 10-2.

23) The rate constant for this reaction is __________ s-1. A) 0.013. B) 0.030. C) 0.14. D) 3.0. E) 3.1 × 10-3.

24) The half-life of this reaction is __________ s. A) 0.97. B) 7.1. C) 5.0. D) 3.0. E) 0.14.

25) The rate constant for this reaction is __________ s-1. A) 6.9 × 10-2. B) 3.0 × 10-2. C) 14. D) 0.46. E) 4.0 × 102.

26) The concentration of A is __________ M after 40.0 s. A) 1.3 × 10-2. B) 1.2. C) 0.17. D) 3.5 × 10-4. E) 0.025.

27) The rate constant of a first-order process that has a half-life of 225 s is __________ s-1. A) 0.693. B) 3.08 × 10-3. C) 1.25. D) 12.5. E) 4.44 × 10-3.

28) The rate constant of a first-order process that has a half-life of 3.50 min is __________ s-1. A) 0.693. B) 1.65 × 10-2. C) 1.98. D) .198. E) 3.30 × 10-3.

29) The reaction A (aq) → B (aq) is first order in [A]. A solution is prepared with [A] = 1.22 M. The following data are obtained as the reaction proceeds: The rate constant for this reaction is __________ s-1. A) 0.23. B) 1.0. C) 0.17. D) 0.12. E) -0.12.

30) One difference between first- and second-order reactions is that __________. A) 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. B) the rate of both first-order and second-order reactions do not depend on reactant concentrations. C) the rate of a first-order reaction depends on reactant concentrations; the rate of a second-order reaction does not depend on reactant concentrations. D) a first-order reaction can be catalyzed; a second-order reaction cannot be catalyzed. E) None of the above are true.

31) At elevated temperatures, methylisonitrile (CH3NC) isomerizes to acetonitrile (CH3CN): CH3NC (g) → CH3CN (g) The reaction is first order in methylisonitrile. The attached graph shows data for the reaction obtained at 198.9°C. The rate constant for the reaction is __________ s-1. A) -1.9 × 104. B) +1.9 × 104. C) -5.2 × 10-5. D) +5.2 × 10-5. E) +6.2.

32) The decomposition of N2O5 in solution in carbon tetrachloride proceeds via the reaction 2N2O5 (soln) → 4NO2 (soln) + O2 (soln) The reaction is first order and has a rate constant of 4.82 × 10-3 s-1 at 64°C. The rate law for the reaction is rate = __________. A) k[N2O5]2. B) k (["N" "O" _2 ]^4 [O_2 ])/[N_2 O_5 ]^2. C) k[N2O5]. D) k [N_2 O_5 ]^2/(["N" "O" _2 ]^4 [O_2 ] ). E) 2k[N2O5].

33) As the temperature of a reaction is increased, the rate of the reaction increases because the __________. A) reactant molecules collide less frequently. B) reactant molecules collide more frequently and with greater energy per collision. C) activation energy is lowered. D) reactant molecules collide less frequently and with greater energy per collision. E) reactant molecules collide more frequently with less energy per collision.

34) The rate of a reaction depends on __________. A) collision frequency. B) collision energy. C) collision orientation. D) all of the above. E) none of the above.

35) Which energy difference in the energy profile below corresponds to the activation energy for the forward reaction?. A) x. B) y. C) x + y. D) x - y. E) y - x.

36) In the energy profile of a reaction, the species that exists at the maximum on the curve is called the __________. A) product. B) activated complex. C) activation energy. D) enthalpy of reaction. E) atomic state.

37) In the Arrhenius equation, k = Ae-Ea/RT __________ is the frequency factor. A) k. B) A. C) e. D) Ea. E) R.

38) In general, as temperature goes up, reaction rate __________. A) goes up if the reaction is exothermic. B) goes up if the reaction is endothermic. C) goes up regardless of whether the reaction is exothermic or endothermic. D) stays the same regardless of whether the reaction is exothermic or endothermic. E) stays the same if the reaction is first order.

39) In general, as temperature goes down, reaction rate __________. A) goes down if the reaction is exothermic. B) goes down if the reaction is endothermic. C) stays the same regardless of whether the reaction is exothermic or endothermic. D) goes down regardless of whether the reaction is exothermic or endothermic. E) none of the above.

40) At elevated temperatures, methylisonitrile (CH3NC) isomerizes to acetonitrile (CH3CN): 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) 160. B) 1.6 × 105. C) 4.4 × 10-7. D) 4.4 × 10-4. E) 1.9 × 104.

45) Of the following, __________ will lower the activation energy for a reaction. A) increasing the concentrations of reactants. B) raising the temperature of the reaction. C) adding a catalyst for the reaction. D) removing products as the reaction proceeds. E) increasing the pressure.

46) The rate law of the overall reaction A + B → C is rate = k[A]2. Which of the following will not increase the rate of the reaction?. A) increasing the concentration of reactant A. B) increasing the concentration of reactant B. C) increasing the temperature of the reaction. D) adding a catalyst for the reaction. E) All of these will increase the rate.

47) A catalyst can increase the rate of a reaction __________. A) by changing the value of the frequency factor (A). B) by increasing the overall activation energy (Ea) of the reaction. C) by lowering the activation energy of the reverse reaction. D) by providing an alternative pathway with a lower activation energy. E) All of these are ways that a catalyst might act to increase the rate of reaction.

1) Consider the following reaction: 3A → 2B The average rate of appearance of B is given by Δ[B]/Δt. Comparing the rate of appearance of B and the rate of disappearance of A, we get Δ[B]/Δt = __________ × (-Δ[A]/Δt). A) -2/3. B) +2/3. C) -3/2. D) +1. E) +3/2.

2) Which substance in the reaction below either appears or disappears the fastest? 4NH3 + 7O2 → 4NO2 + 6H2O. A) NH3. B) O2. C) NO2. D) H2O. E) The rates of appearance/disappearance are the same for all of these.

3) Consider the following reaction: A → 2C The average rate of appearance of C is given by Δ[C]/Δt. Comparing the rate of appearance of C and the rate of disappearance of A, we get Δ[C]/Δt = __________ × (-Δ[A]/Δt). A) +2. B) -1. C) +1. D) +1/2. E) -1/2.

4) The average rate of disappearance of A between 10 s and 20 s is __________ mol/s. A) 2.2 × 10-3. B) 1.1 × 10-3. C) 4.4 × 10-3. D) 454. E) 9.90 × 10-3.

5) The average rate of disappearance of A between 20 s and 40 s is __________ mol/s. A) 8.5 × 10-4. B) 1.7 × 10-3. C) 590. D) 7.1 × 10-3. E) 1.4 × 10-3.

8) How many moles of B are present at 10 s?. A) 0.011. B) 0.220. C) 0.110. D) 0.014. E) 1.4 × 10-3.

16) At elevated temperatures, dinitrogen pentoxide decomposes to nitrogen dioxide and oxygen: 2N2O5(g) → 4NO2 (g) + O2 (g) When the rate of formation of NO2 is 5.5 × 10-4 M/s, the rate of decomposition of N2O5 is ________ M/s. A) 2.2 × 10-3. B) 1.4 × 10-4. C) 10.1 × 10-4. D) 2.8 × 10-4. E) 5.5 × 10-4.

17) At elevated temperatures, methylisonitrile (CH3NC) isomerizes to acetonitrile (CH3CN): CH3NC (g) → CH3CN (g) At the start of the experiment, there are 0.200 mol of reactant (CH3NC) and 0 mol of product (CH3CN) in the reaction vessel. After 25 min of reaction, 0.108 mol of reactant (CH3NC) remain. The average rate of decomposition of methyl isonitrile, CH3NC, in this 25 min period is __________ mol/min. A) 3.7 × 10-3. B) 0.092. C) 2.3. D) 4.3 × 10-3. E) 0.54.

18) A reaction was found to be second order in carbon monoxide concentration. The rate of the reaction __________ if the [CO] is doubled, with everything else kept the same. A) doubles. B) remains unchanged. C) triples. D) increases by a factor of 4. E) is reduced by a factor of 2.

19) If the rate law for the reaction 2A + 3B → products is first order in A and second order in B, then the rate law is rate = __________. A) k[A][B]. B) k[A]2[B]3. C) k[A][B]2. D) k[A]2[B]. E) k[A]2[B]2.

21) The overall order of a reaction is 1. The units of the rate constant for the reaction are __________. A) M/s. B) M-1s-1. C) 1/s. D) 1/M. E) s/M2.

22) The overall order of a reaction is 2. The units of the rate constant for the reaction are __________. A) M/s. B) M-1s-1. C) 1/s. D) 1/M. E) s/M2.

23) The kinetics of the reaction below were studied and it was determined that the reaction rate increased by a factor of 9 when the concentration of B was tripled. The reaction is __________ order in B. A + B → P. A) zero. B) first. C) second. D) third. E) one-half.

24) The kinetics of the reaction below were studied and it was determined that the reaction rate did not change when the concentration of B was tripled. The reaction is __________ order in B. A + B → P. A) zero. B) first. C) second. D) third. ) one-half.

25) A reaction was found to be third order in A. Increasing the concentration of A by a factor of 3 will cause the reaction rate to __________. A) remain constant. B) increase by a factor of 27. C) increase by a factor of 9. D) triple. E) decrease by a factor of the cube root of 3.

26) A reaction was found to be zero order in A. Increasing the concentration of A by a factor of 3 will cause the reaction rate to __________. A) remain constant. B) increase by a factor of 27. C) increase by a factor of 9. D) triple. E) decrease by a factor of the cube root of 3.

27) The order of the reaction in A is __________. A) 1. B) 2. C) 3. D) 4. E) 0.

28) The order of the reaction in B is __________. A) 1. B) 2. C) 3. D) 4. E) 0.

29) The overall order of the reaction is __________. A) 1. B) 2. C) 3. D) 4. E) 0.

30) The following reaction occurs in aqueous solution: NH4+ (aq) + NO2- → N2 (g) + 2H2O (l) The data below is obtained at 25°C. The order of the reaction in NH4+ is __________. A) -2. B) -1. C) +2. D) +1. E) 0.

34) The graph shown below depicts the relationship between concentration and time for the following chemical reaction. The slope of this line is equal to __________. A) k. B) -1/k. C) ln[A]o. D) -k. E) 1/k.

35) The reaction below is first order in [H2O2]: 2H2O2 (l) → 2H2O (l) + O2 (g) A solution originally at 0.600 M H2O2 is found to be 0.075 M after 54 min. The half-life for this reaction is __________ min. A) 6.8. B) 18. C) 14. D) 28. E) 54.

1) The rate of disappearance of HBr in the gas phase reaction 2HBr (g) → H2 (g) + Br2 (g) is 0.301 Ms-1 at 150°C. The rate of appearance of Br2 is __________ Ms-1. A) 1.66. B) 0.151. C) 0.0906. D) 0.602. E) 0.549.

3) The combustion of ethylene proceeds by the reaction C2H4(g) + 3O2 (g) → 2CO2 (g) + 2H2O (g) When the rate of disappearance of O2 is 0.28 Ms-1, the rate of appearance of CO2 is __________ Ms-1. A) 0.19. B) 0.093. C) 0.84. D) 0.42. E) 0.56.

2) For the reaction aA + Bb → cC + dD the rate law is __________.

3) If a rate law is second order (reactant), doubling the reactant __________ the reaction rate.

5) Reaction rates are affected by reactant concentrations and temperature. This is accounted for by the __________.

6) The minimum energy to initiate a chemical reaction is the __________.

7) Reaction rate data showing temperature dependence obey an equation devised by __________.

10) A catalyst that is present in the same phase as the reacting molecules is called a __________ catalyst.

11) A catalyst that is present in a different phase from the reacting molecules is called a __________ catalyst.

1) Rates of reaction can be positive or negative. V. F.

2) The instantaneous rate of a reaction can be read directly from the graph of molarity versus time at any point on the graph. V. F.

3) The overall reaction order is the sum of the orders of each reactant in the rate law. V. F.

4) Units of the rate constant of a reaction are independent of the overall reaction order. V. F.

5) The concentration of reactants or products at any time during the reaction can be calculated from the integrated rate law. V. F.

6) The rate of a second order reaction can depend on the concentrations of more than one reactant. V. F.

7) The half-life for a first order rate law depends on the starting concentration. V. F.