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Chemistry, 7/e
Raymond Chang, Williams College
Chemical Kinetics

Self Assessment B



1

For the reaction 4 NH3(g) + 5 O22(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
2

The compound RX3 decomposes according to the chemical equation 3 RX3 ----> R + R2X3 + 3 X2. In an experiment, the following data were collected for this decomposition at 100 oC. What is the average rate of reaction over the entire experiment?
A)0.0028 M/s
B)0.0452 M/s
C)0.0014 M/s
D)-0.0028 M/s
E)0.0057 M/s
3

Consider the reaction CH3Cl + OH- ----> CH3OH + Cl-. At some temperature, the following data are collected.
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.
4

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)11.8 min
D)2.45 min
E)None of the above
5

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?
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
6

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)7.13x 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
7

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]
8

Which of the following is a likely mechanism for the reaction (CH3)3 Cl + OH- ----> (CH3)3OH + Cl-, which is first order in (CH3)3Cl 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
9

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
10

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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