Q: The half-life of a first-order reaction is 10 minutes. What is the value of the rate constant $$k$$?

$$k = 0.0693\ \text{min}^{-1}$$

Q: Which of the following is the correct equilibrium expression for the reaction $$2\text{NO}_2(g) \rightleftharpoons 2\text{NO}(g) + \text{O}_2(g)$$?

$$K = \frac{[\text{NO}]^2[\text{O}_2]}{[\text{NO}_2]^2}$$

Q: A mixture initially contains 1.0 mol of $$\text{N}_2$$, 3.0 mol of $$\text{H}_2$$, and 2.0 mol of $$\text{NH}_3 in a 1.0 L $$vessel at equilibrium for the reaction $$\text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g). If $$more $$\text{N}_2 is $$added, what will happen according to Le Chatelier’s principle?

The equilibrium will shift to the right, producing more $$\text{NH}_3.$$

Q: For the reaction $$\text{A} \rightleftharpoons \text{B}$$, the equilibrium constant $$K is $$much less than 1. Which of the following is true at equilibrium?

The concentration of $$\text{A} is $$much greater than that of $$\text{B}.$$

Question 1

A reaction is observed to proceed twice as fast when the temperature is increased from 25°C to 35°C. Which of the following best explains this observation?

Accepted Answer

The frequency of effective collisions between reactant molecules increases with temperature.

Question 2

Given the following data for the reaction $$A + 2B \rightarrow C$$:

Experiment 1: [A] = 0.10 M, [B] = 0.10 M, Rate = 0.020 M/s
Experiment 2: [A] = 0.20 M, [B] = 0.10 M, Rate = 0.040 M/s
Experiment 3: [A] = 0.10 M, [B] = 0.20 M, Rate = 0.080 M/s

What is the rate law for this reaction?

Accepted Answer

$$	ext{Rate} = k[A][B]^2$$

Question 3

A catalyst increases the rate of a chemical reaction by:

Accepted Answer

Decreasing the activation energy.

Question 4

For a first-order reaction, which of the following equations correctly relates the concentration of reactant $$[A] at $$time $$t to $$its initial concentration $$[A]_0$$ and the rate constant $$k$$?

Accepted Answer

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

Question 5

A reaction has a rate law $$	ext{Rate} = k[A]^0[B]^1. If $$the concentration of $$A is $$doubled and $$B is $$tripled, what happens to the rate?

Accepted Answer

The rate increases by a factor of 3.

Question 6

Which of the following best describes the effect of increasing the surface area of a solid reactant in a heterogeneous reaction?

Accepted Answer

It increases the rate by providing more area for collisions.

Question 7

Consider the following mechanism for a reaction:
Step 1 (slow): $$A + B \rightarrow C$$
Step 2 (fast): $$C + D \rightarrow E$$
What is the rate law for the overall reaction?

Accepted Answer

$$	ext{Rate} = k[A][B]$$

Question 8

A reaction is found to be second order overall. Which of the following could be a correct rate law for this reaction?

Accepted Answer

$$	ext{Rate} = k[A]^2$$

Question 9

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

Accepted Answer

The rate remains unchanged.

Question 10

The half-life of a first-order reaction is 10 minutes. What is the value of the rate constant $$k$$?

Accepted Answer

$$k = 0.0693\ 	ext{min}^{-1}$$

Question 11

Which of the following is the correct equilibrium expression for the reaction $$2	ext{NO}_2(g) ightleftharpoons 2	ext{NO}(g) + 	ext{O}_2(g)$$?

Accepted Answer

$$K = \frac{[	ext{NO}]^2[	ext{O}_2]}{[	ext{NO}_2]^2}$$

Question 12

A mixture initially contains 1.0 mol of $$	ext{N}_2$$, 3.0 mol of $$	ext{H}_2$$, and 2.0 mol of $$	ext{NH}_3 in a 1.0 L $$vessel at equilibrium for the reaction $$	ext{N}_2(g) + 3	ext{H}_2(g) ightleftharpoons 2	ext{NH}_3(g). If $$more $$	ext{N}_2 is $$added, what will happen according to Le Chatelier’s principle?

Accepted Answer

The equilibrium will shift to the right, producing more $$	ext{NH}_3.$$

Question 13

For the reaction $$	ext{A} ightleftharpoons 	ext{B}$$, the equilibrium constant $$K is $$much less than 1. Which of the following is true at equilibrium?

Accepted Answer

The concentration of $$	ext{A} is $$much greater than that of $$	ext{B}.$$

Question 14

A reaction mixture at a certain temperature contains $$[	ext{CO}] = 0.20\ 	ext{M}$$, $$[	ext{Cl}_2] = 0.10\ 	ext{M}$$, and $$[	ext{COCl}_2] = 0.30\ 	ext{M}$$ for the reaction $$	ext{CO}(g) + 	ext{Cl}_2(g) ightleftharpoons 	ext{COCl}_2(g). If$$ $$K = 2.0$$, what is the value of the reaction quotient $$Q$$ and in which direction will the reaction proceed to reach equilibrium?

Accepted Answer

$$Q = 15$$, reaction proceeds to the left.

Question 15

Which of the following statements about chemical equilibrium is correct?

Accepted Answer

At equilibrium, the rates of the forward and reverse reactions are equal.

Question 16

A certain reaction is first order in $$A$$ and second order in $$B. If $$the initial rate is $$0.10\ 	ext{M/s}$$ when $$[A] = 0.20\ 	ext{M}$$ and $$[B] = 0.10\ 	ext{M}$$, what will the rate be if $$[A] is $$doubled and $$[B] is $$tripled?

Accepted Answer

$$0.60\ 	ext{M/s}$$

Question 17

Which of the following is a correct statement about the effect of a catalyst on a reaction at equilibrium?

Accepted Answer

A catalyst does not affect the position of equilibrium.

Question 18

For a zeroth-order reaction, which of the following is true?

Accepted Answer

The rate is independent of the concentration of reactant.

Question 19

A student is studying the decomposition of hydrogen peroxide, $$2	ext{H}_2	ext{O}_2(aq) ightarrow 2	ext{H}_2	ext{O}(l) + 	ext{O}_2(g)$$, and finds that the reaction is first order in $$	ext{H}_2	ext{O}_2. If $$the initial concentration is $$0.80\ 	ext{M}$$ and the rate constant $$k = 0.25\ 	ext{min}^{-1}$$, what is the concentration after 4.0 minutes?

Accepted Answer

$$[	ext{H}_2	ext{O}_2] = 0.16\ 	ext{M}$$

Question 20

Which of the following best describes the use of an ICE (Initial-Change-Equilibrium) table in equilibrium calculations?

Accepted Answer

It is used to calculate the concentrations of all species at equilibrium.

Chemical Kinetics and Chemical Equilibrium: Study Guide Notes

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