Question 1

Which integrated rate law equation would you use to determine the concentration of a reactant at any time for a first-order reaction?

Accepted Answer

$$\ln [A]_t = -kt + \ln [A]_0$$

Question 2

A plot of $$\ln [CH_3NC]$$ versus time for the decomposition of methyl isonitrile is linear. What does this indicate about the order of the reaction?

Accepted Answer

The reaction is first order.

Question 3

Given the following data for the decomposition of $$NO_2$$:

| Time (s) | [NO2] (M) |
|---------|-----------|
| 0.0     | 0.01000   |
| 50.0    | 0.00787   |
| 100.0   | 0.00649   |
| 200.0   | 0.00481   |
| 300.0   | 0.00380   |

Which plot would be linear if the reaction is second order in $$NO_2$$?

Accepted Answer

A plot of $$1/[NO_2$] vs. $$time

Question 4

For a zero-order reaction, which of the following statements is true about the concentration of the reactant over time?

Accepted Answer

It decreases linearly with time.

Question 5

The half-life of a first-order reaction is given by which equation?

Accepted Answer

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

Question 6

Mercury(II) is eliminated from the body by a first-order process with a half-life of 6 days. If the initial concentration is $$8.0 	imes 10$$^{-6}$$ M, what is the concentration after 18 days?

Accepted Answer

$$2.0 	imes 10$$^{-6}$$ M

Question 7

Which of the following factors does NOT affect the rate of a chemical reaction according to the collision model?

Accepted Answer

The overall energy change $$\Delta E of $$the reaction

Question 8

According to the Arrhenius equation, what is the effect of increasing temperature on the rate constant $$k$$?

Accepted Answer

The rate constant increases.

Question 9

Given the Arrhenius equation $$k = Ae$$^{-E_a/RT}$$, what does the frequency factor A$ represent?

Accepted Answer

The frequency of collisions and the orientation factor

Question 10

A reaction mechanism consists of the following steps:
Step 1: $$O_3(g$$) + $$NO_2(g$$) \rightarrow $$NO_3(g$$) + $$O_2(g$$)$$ (slow)
Step 2: NO_3$(g) + NO_2$(g) \rightarrow N_2O_5(g) ($$fast)
What is the rate law for the overall reaction?

Accepted Answer

Rate = $$k[O_3$][NO_2$]$$

Question 11

Which of the following best describes an intermediate in a reaction mechanism?

Accepted Answer

A species that is formed and consumed during the reaction mechanism

Question 12

For the reaction $$2NO_2(g) \rightarrow 2NO(g) + O_2$(g)$$, the plot of $$1/[NO_2$]$$ versus time is linear. What is the order of the reaction with respect to $$NO_2$$?

Accepted Answer

Second order

Question 13

Which of the following is true about the half-life of a first-order reaction?

Accepted Answer

It is independent of the initial concentration.

Question 14

A potential energy diagram for a reaction shows a high peak between reactants and products. What does this peak represent?

Accepted Answer

The activation energy $$E_a$$

Question 15

If a reaction is zero order in $$[A]$$, what is the integrated rate law?

Accepted Answer

$$[A]_t = [A]_0 - kt$$

Question 16

Which of the following is a correct statement about the rate-determining step in a multistep reaction?

Accepted Answer

It is the slowest step in the mechanism.

Question 17

For a reaction with the Arrhenius equation $$k = Ae$$^{-E_a/RT}$$, what is the effect of increasing the activation energy E_a$ on the rate constant k$ at a constant temperature?

Accepted Answer

The rate constant decreases.

Question 18

A reaction is found to be first order in $$A. If $$the initial concentration of $$A is $$doubled, what happens to the half-life of the reaction?

Accepted Answer

It remains the same.

Question 19

Which of the following best explains why increasing temperature generally increases the rate of a chemical reaction?

Accepted Answer

It increases the fraction of molecules with energy greater than $$E_a.$$

Question 20

Which of the following is the correct rate law for the elementary reaction $$H_2S(aq) + Cl_2$(aq) \rightarrow S(s) + 2H^+(aq) + 2Cl^-(aq)$$?

Accepted Answer

Rate = $$k[H_2S][Cl_2$]$$

Integrated Rate Laws, Reaction Kinetics, and Mechanisms in General Chemistry

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