Question 1

Which of the following best describes the units of the rate constant $k$ for a second-order reaction?

Accepted Answer

$\mathrm{M}^{-1} \ s^{-1}$

Question 2

For the reaction $A + B ightarrow C$, the rate law is $	ext{rate} = k[A][B]$. What are the units of $k$?

Accepted Answer

$\mathrm{M}^{-1} \ s^{-1}$

Question 3

A zero-order reaction has a rate law $	ext{rate} = k$. What are the units of $k$ for this reaction?

Accepted Answer

$\mathrm{M} \ s^{-1}$

Question 4

In the enzyme-catalyzed reaction $E + S \underset{k_{-1}}{\overset{k_1}{\rightleftharpoons}} ES \overset{k_2}{\rightarrow} E + P$, what are the units of $k_2$?

Accepted Answer

$s^{-1}$

Question 5

Given the rate law $	ext{rate} = k[E][S]$ for the formation of ES in an enzyme-catalyzed reaction, what is the overall order of the reaction?

Accepted Answer

Second order

Question 6

If the rate constant $k$ for a reaction has units of $s^{-1}$, what is the most likely order of the reaction?

Accepted Answer

First order

Question 7

For the breakdown of ES to E + S in the enzyme-catalyzed reaction, the rate law is $	ext{rate} = k_{-1}[ES]$. What are the units of $k_{-1}$?

Accepted Answer

$s^{-1}$

Question 8

A reaction has the rate law $	ext{rate} = k[A]^2$. If the units of rate are $\mathrm{M} \ s^{-1}$, what are the units of $k$?

Accepted Answer

$\mathrm{M}^{-1} \ s^{-1}$

Question 9

Which of the following statements is TRUE regarding the sum of exponents in a rate law?

Accepted Answer

The sum of the exponents equals the overall reaction order.

Question 10

In a reaction where $	ext{rate} = k[A][B]$, doubling the concentration of both $A$ and $B$ will increase the rate by what factor?

Accepted Answer

Four

Question 11

If a reaction is third order overall, which of the following could be the units of its rate constant $k$?

Accepted Answer

$\mathrm{M}^{-2} \ s^{-1}$

Question 12

Which of the following best explains why the units of the rate constant $k$ change with reaction order?

Accepted Answer

The units of $k$ must compensate for the concentration terms in the rate law to yield units of $\mathrm{M} \ s^{-1}$ for rate.

Question 13

For the enzyme-catalyzed reaction $E + S \underset{k_{-1}}{\overset{k_1}{\rightleftharpoons}} ES \overset{k_2}{\rightarrow} E + P$, which rate constant describes the breakdown of ES to E + P?

Accepted Answer

$k_2$

Question 14

A student claims that for any reaction, the units of the rate constant $k$ are always $s^{-1}$. Is this correct?

Accepted Answer

No, the units of $k$ depend on the overall reaction order.

Question 15

If the rate law for a reaction is $	ext{rate} = k[A]$, and the rate constant $k$ is measured as $0.5 \ s^{-1}$, what is the order of the reaction?

Accepted Answer

First order

Rate Constant Units and Enzyme Kinetics

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