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1 | | For the reaction 4 NH3(g) + 5 O2(g) --> 4 NO(g) + 6 H2O(g), -D[NH3]/Dt = 2.6 x 10-3 M/s at a particular time. What is the value of -D[O2]/Dt at the same instant? |
| | A) | 1.3 x 10-2 |
| | B) | 2.1 x 10-3 M/s |
| | C) | 2.6 x 10-3 M/s |
| | D) | 3.3 x 10-3 M/s |
| | E) | 5.2 x 102 M/s |
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2 | | Consider the reaction CH3Cl + OH- ----> CH3OH + Cl-. At some temperature, the following data are collected:
1. When [CH3Cl] is doubled, the rate doubles.
2. When [OH-] doubles, the rate doubles. |
| | A) | The reaction is first order with respect to CH3Cl |
| | B) | The reaction is first order with respect to OH-. |
| | C) | The reaction is second order overall |
| | D) | All of the above. |
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3 | | What is the half-life of a first order reaction for which k = 9.8 x 10-4 s-1? |
| | A) | 0.0014 min |
| | B) | 707 min |
| | C) | 12 min |
| | D) | 2.45 min |
| | E) | None of the above |
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4 | | At 25 oC, the second order rate constant for the reaction I- + ClO- ----> IO- + Cl- is 0.0805 M-1s-1. If a solution is initially 4.05 x 10-3 M with respect to each reactant, what will be the concentration of each species present after 250 s? (Treat it as if there is only one reactant.) |
| | A) | 4.96 x 10-3 M |
| | B) | 2.01 x 10-3 M |
| | C) | 2.67 x 10-3 M |
| | D) | 3.75 x 10-3 M |
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5 | | A second order reaction whose rate constant at 700 oC was found to be 4.0 x 10-3 L/mol.s has an activation energy of 35.0 kJ/mol. What is the rate constant for this reaction at 850 oC? |
| | A) | 7.1x 10-3 L/mol·s |
| | B) | 5.25 x 10-6 L/mol·s |
| | C) | 5.78 x 10-2 L/mol·s |
| | D) | 1.8 x 10-3 L/mol·s |
| | E) | 1.0 x 10-3 L/mol·s |
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6 | | Which of the following equations represents the rate law for the following elementary process: A + B ----> C + D? |
| | A) | Rate = k[C][D] |
| | B) | Rate = k[A] |
| | C) | Rate = k[A][B]2 |
| | D) | Rate = k[A][B] |
| | E) | Rate = k[B] |
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7 | | Which of the following is a likely mechanism for the reaction (CH3)3 CCl + OH- ----> (CH3)3COH + Cl-, which is first order in (CH3)3CCl and first order overall? |
| | A) | A one-step mechanism involving a transition state that contains two hydroxide ions "attached" to the carbon atom of (CH3)3Cl |
| | B) | A one-step mechanism involving a transition state that has a carbon partially bonded to both chlorine and oxygen |
| | C) | A two-step mechanism in which the chlorine leaves (CH3) 3Cl in a slow step, followed by rapid attack of the intermediate by the hydroxide ion |
| | D) | A two-step mechanism in which the chlorine leaves (CH3)3Cl in a rapid step, followed by the slow attack of the intermediate by the hydroxide ion |
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8 | | Below is a possible mechanism for the oxidation of bromide ions by hydrogen peroxide in aqueous acid solution. What is the overall reaction equation for this process?H+ + H2O2 ----> H2O+--OH (rapid equilibrium)H2O+--OH + Br- ----> HOBr + H2O (slow)HOBr + H+ ----> Br2 + H2O (fast) |
| | A) | 2 H+ + H2O2 + Br- + HOBr ----> H2O+--OH + Br2 + H2 O |
| | B) | H2O+--OH + H++ Br- ----> Br2 + H2O |
| | C) | 2 H+ + 2 Br- + H2O2 ----> Br2 + 2 H2O |
| | D) | 2 H2O+--OH + 2 Br- ----> H2O2 + Br2 + 2 H2O |
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9 | | A catalyst is effective because |
| | A) | it supplies energy to the reactant molecules, allowing more of them to achieve energies in excess of the activation energy for the reaction |
| | B) | it increases the temperature of the molecules in the reaction mixture |
| | C) | it increases the number of collisions between molecules |
| | D) | it lowers the activation energy of the reaction by providing a lower energy mechanism or pathway |
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10 | | For the following reaction, the rate law is found to be Rate = k[Ce4+][Mn2+]. 2 Ce4+ + Tl+ ---> 2 Ce3+ + Tl3+One mechanism for this reaction, containing the following elementary steps, is shown below:
Ce4+ + Mn2+ ---> Ce3+ + Mn3+Ce4+ + Mn3+ ---> Ce3+ + Mn4+Tl+ + Mn4+ ---> Tl3+ + Mn2+ |
| | A) | There is no catalyst and no intermediate. |
| | B) | There is no catalyst, but Mn2+ is the intermediate. |
| | C) | Mn3+ is the catalyst and there is no intermediate. |
| | D) | Mn2+ is the catalyst and Mn3+ and Mn4+ are the intermediates. |
| | E) | Mn4+ is the catalyst and Mn2+ and Mn3+ are the intermediates. |
| | F) | Ce3+ is the catalyst and Tl+ and Mn4+ are the intermediates. |
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