Question 1

For the reaction $$A ightarrow$$ products, the following data were collected:

$$\begin{array}{cc}
[A] \ (M) & 	ext{Initial Rate} \ (M/s) \
0.10 & 0.015 \
0.20 & 0.030 \
0.40 & 0.060 \
\end{array}$$

What is the order of the reaction with respect to $$A$$?

Accepted Answer

First order

Question 2

A reaction has a rate law $$	ext{Rate} = k[NO]^2[O_2$]. $$What is the overall order of the reaction?

Accepted Answer

Third order

Question 3

For a first-order reaction, which of the following plots yields a straight line?

Accepted Answer

$$\ln[A] vs. $$time

Question 4

A reaction is found to be second order in $$A. If $$the initial rate is $$0.0100 M/s at$$ $$[A] = 0.100 M$$, what is the initial rate at $$[A] = 0.500 M$$?

Accepted Answer

$$0.250 M/s$$

Question 5

Which of the following statements about zero-order reactions is correct?

Accepted Answer

The rate is constant and independent of the concentration of the reactant.

Question 6

Given the following data for the reaction $$NO_2 + CO$$ ightarrow NO + $$CO_2$$:

$$\begin{array}{ccc}
[NO_2$] (M) & [CO] (M) & 	ext{Initial Rate} (M/s) \
0.10 & 0.10 & 0.0021 \
0.20 & 0.10 & 0.0082 \
0.20 & 0.20 & 0.0083 \
0.40 & 0.10 & 0.033 \
\end{array}$$

What is the order of the reaction with respect to $$CO$$?

Accepted Answer

Zero order

Question 7

The integrated rate law for a second-order reaction is:

Accepted Answer

$$\dfrac{1}{[A]_t} = kt + \dfrac{1}{[A]_0}$$

Question 8

A first-order reaction has a half-life of 25 minutes. If the initial concentration of $$A is 0.300 M$$, what is the concentration of $$A$$ after 50 minutes?

Accepted Answer

0.150 M

Question 9

Which of the following best explains why reaction rates generally increase with increasing temperature?

Accepted Answer

Because a greater fraction of molecules have enough thermal energy to surmount the activation barrier.

Question 10

The Arrhenius equation is $$k = Ae$$^{-E_a/RT}$$. What does the exponential factor e$$^{-E_a/RT}$$ represent?

Accepted Answer

The fraction of molecules with enough energy to overcome the activation barrier.

Question 11

A decomposition reaction slows down as it proceeds, and its half-life depends on the initial concentration. Which statement is most likely true for this reaction?

Accepted Answer

The half-life increases as the initial concentration increases.

Question 12

Which of the following is the correct expression for the half-life of a first-order reaction?

Accepted Answer

$$t_{1/2} = \dfrac{0.693}{k}$$

Question 13

For a reaction with the rate law $$	ext{Rate} = k[A][B]^2$$, what is the effect on the rate if $$[A] is $$doubled and $$[B] is $$tripled?

Accepted Answer

The rate increases by a factor of 18.

Question 14

Which of the following is true for a zero-order reaction?

Accepted Answer

A plot of $$[A] vs. $$time is a straight line with a negative slope.

Question 15

The rate constant $$k$$ for a reaction is found to increase with temperature. According to the Arrhenius equation, which of the following is true?

Accepted Answer

The exponential factor increases as temperature increases.

Question 16

A reaction has a rate law $$	ext{Rate} = k[A]^2. If $$the initial concentration of $$A is$$ $$0.10 M $$and the rate constant $$k is$$ $$0.50 M$^{-1}s$^{-1}$$, what is the initial rate?

Accepted Answer

$$0.0050 M/s$$

Question 17

Which of the following best describes the activated complex in a chemical reaction?

Accepted Answer

A chemical species with partially broken and partially formed bonds at the highest energy point along the reaction path.

Question 18

If two reactions have identical frequency factors but different activation energies, which reaction will have the greater rate constant at room temperature?

Accepted Answer

The reaction with the lower activation energy.

Question 19

A student is analyzing a reaction and finds that a plot of $$1/[A] vs. $$time is linear. What is the order of the reaction?

Accepted Answer

Second order

Question 20

Which of the following is the correct two-point form of the Arrhenius equation for comparing rate constants at two temperatures?

Accepted Answer

$$\ln\left(\dfrac{k_2$}{k_1$}\right) = -\dfrac{E_a}{R}\left(\dfrac{1}{T_2$} - \dfrac{1}{T_1$}\right)$$

Chemical Kinetics: Reaction Rates, Rate Laws, and Temperature Effects

Study Guide - Practice Questions

Study Guide - Flashcards