Question 1

Which of the following changes will increase the rate of a chemical reaction according to the collision theory?

Accepted Answer

Increasing the surface area of a solid reactant

Question 2

A reaction has a rate law given by $$ 	ext{rate} = k[A]^2[B] . If $$the concentration of $$[A] is $$doubled and $$[B] is $$halved, by what factor does the reaction rate change?

Accepted Answer

It is increased by a factor of 2

Question 3

Which of the following statements best describes the role of a catalyst in a chemical reaction?

Accepted Answer

It lowers the activation energy, increasing the rate of both the forward and reverse reactions

Question 4

Given the reaction $$ 2NO_2(g) \rightleftharpoons 2NO(g) + O_2$(g) $$, which of the following expressions represents the equilibrium constant $$K_c$$?

Accepted Answer

$$ K_c = \frac{[NO]^2[O_2$]}{[NO_2$]^2} $$

Question 5

For the reaction $$ A \rightarrow B $$, the half-life is independent of the initial concentration. What is the order of the reaction?

Accepted Answer

First order

Question 6

A student is studying the decomposition of hydrogen peroxide: $$ 2H_2O_2(aq) \rightarrow 2H_2O(l) + O_2$(g) . If $$the rate of disappearance of $$H_2O_2 is$$ $$0.10 M/s$$, what is the rate of appearance of $$O_2$$?

Accepted Answer

$$0.05 M/s$$

Question 7

Which of the following best describes a reaction intermediate?

Accepted Answer

A species that is formed and consumed during the reaction mechanism

Question 8

Consider the following equilibrium: $$ N_2$(g) + 3H_2(g) \rightleftharpoons 2NH_3(g) . If $$the concentration of $$NH_3 is $$increased, what will happen according to Le Chatelier's Principle?

Accepted Answer

The equilibrium will shift to the left, producing more $$N_2$$ and $$H_2$$

Question 9

Which of the following is true about the rate-determining step in a reaction mechanism?

Accepted Answer

It is the slowest step and limits the overall reaction rate

Question 10

A reaction has an equilibrium constant $$K_c = 1.2 	imes 10$$^{-5}$$. Which statement is correct?

Accepted Answer

At equilibrium, reactants are favored

Question 11

For the reaction $$ 2A + B ightarrow C $$, the rate law is $$ 	ext{rate} = k[A][B] . If $$the initial concentration of $$A is$$ $$0.10 M $$and $$B is$$ $$0.20 M$$, and $$k = 0.50 M$^{-1}s$^{-1}$$, what is the initial rate?

Accepted Answer

$$0.005 M/s$$

Question 12

Which of the following best describes a dynamic chemical equilibrium?

Accepted Answer

The forward and reverse reaction rates are equal

Question 13

A reaction is exothermic and has a negative enthalpy change ($$ \Delta H \u003c 0 ). $$What will happen to the equilibrium position if the temperature is increased?

Accepted Answer

The equilibrium will shift toward the reactants

Question 14

Which of the following is the correct expression for the reaction quotient $$Q_c$$ for the reaction $$ aA + bB \rightleftharpoons cC + dD $$?

Accepted Answer

$$ Q_c = \frac{[C]^c[D]^d}{[A]^a[B]^b} $$

Question 15

A reaction has a rate constant $$k$$ that increases significantly with temperature. Which of the following best explains this observation?

Accepted Answer

More molecules have sufficient energy to overcome the activation barrier

Question 16

Which of the following is a correct statement about heterogeneous catalysis?

Accepted Answer

The catalyst provides a surface for the reaction to occur

Question 17

For the reaction $$ 2SO_2(g) + O_2$(g) \rightleftharpoons 2SO_3(g) $$, what will happen if the volume of the reaction vessel is decreased at constant temperature?

Accepted Answer

The equilibrium will shift toward the side with fewer moles of gas

Question 18

Which of the following is the best definition of the rate constant $$k in a $$rate law?

Accepted Answer

It is a proportionality constant that relates the rate of reaction to the concentrations of reactants

Question 19

A reaction mechanism consists of the following steps:

Step 1: $$A + B \rightarrow C ($$slow)
Step 2: $$C + D \rightarrow E ($$fast)

Which step is the rate-determining step, and what is the rate law for the overall reaction?

Accepted Answer

Step 1 is rate-determining; rate law is $$	ext{rate} = k[A][B]$$

Question 20

Which of the following statements about the equilibrium constant $$K is $$correct?

Accepted Answer

It changes with temperature

Chemical Kinetics and Chemical Equilibrium: Key Definitions, Concepts, and Problem-Solving Skills

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