Question 1

Which of the following statements about the equilibrium constant $$K$$ for the reaction $$A \rightleftharpoons B is $$correct?

Accepted Answer

If $$K \u003e 1$$, the concentration of products at equilibrium is greater than that of reactants.

Question 2

A saturated solution of NaCl is heated from $$20\ ^\circ\mathrm{C} to$$ $$40\ ^\circ\mathrm{C}. As $$the temperature increases, how do the rates of dissolution and crystallization compare?

Accepted Answer

The rate of dissolution is faster than the rate of crystallization.

Question 3

For the reaction $$2\mathrm{NO}(g) + \mathrm{Br}_2(g) ightarrow 2\mathrm{NOBr}(g)$$, if the experimentally determined rate law is $$	ext{rate} = k[\mathrm{NO}]^2[\mathrm{Br}_2]$$, which of the following mechanisms is consistent with this rate law?

Accepted Answer

A mechanism where the slow step is $$\mathrm{NO}(g) + \mathrm{Br}_2(g) \rightarrow \mathrm{NOBr}_2(g)$$ followed by $$\mathrm{NOBr}_2(g) + \mathrm{NO}(g) \rightarrow 2\mathrm{NOBr}(g).$$

Question 4

Which of the following best describes the effect of a catalyst on a reaction coordinate diagram?

Accepted Answer

It decreases the activation energy $$E_a$$ for both the forward and reverse reactions.

Question 5

In a multi-step reaction mechanism, what is the rate-determining step?

Accepted Answer

The slowest elementary step.

Question 6

For the reaction $$N_2(g) + 3H_2(g$$) \rightleftharpoons 2NH_3(g)$$, what is the equilibrium constant expression K_c$?

Accepted Answer

$$K_c = \dfrac{[NH_3$]^2}{[N_2$][H_2$]^3}$$

Question 7

Which statement about chemical equilibrium is correct?

Accepted Answer

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

Question 8

The Haber-Bosch process for ammonia synthesis uses a catalyst. What is the main role of the catalyst in this industrial process?

Accepted Answer

To lower the activation energy $$E_a$$ and increase the rate of reaction

Question 9

For the reaction $$A \rightleftharpoons B$$, the rate constants are $$k_f ($$forward) and $$k_r ($$reverse). Which equation correctly relates the equilibrium constant $$K to $$these rate constants?

Accepted Answer

$$K = \dfrac{k_f}{k_r}$$

Question 10

Which of the following is true about the effect of temperature on the equilibrium constant $$K$$ for an exothermic reaction?

Accepted Answer

Increasing temperature decreases $$K.$$

Question 11

In the reaction $$2\mathrm{NO}(g) + \mathrm{Br}_2(g) \rightarrow 2\mathrm{NOBr}(g)$$, which species is an intermediate in the proposed two-step mechanism?

Accepted Answer

$$\mathrm{NOBr}_2$$

Question 12

Which of the following is a correct statement about enzymes as biological catalysts?

Accepted Answer

Enzymes provide an alternative pathway with lower activation energy.

Question 13

For a reaction with the rate law $$	ext{rate} = k[\mathrm{NOBr}_2][\mathrm{NO}]$$, which step is most likely the rate-determining step?

Accepted Answer

A step involving $$\mathrm{NOBr}_2$$ and $$\mathrm{NO}.$$

Question 14

Which of the following is NOT a requirement for a system to reach chemical equilibrium?

Accepted Answer

The concentrations of reactants and products must be equal.

Question 15

For the reaction $$aA + bB \rightleftharpoons cC + dD$$, which equilibrium constant expression is correct?

Accepted Answer

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

Question 16

Which of the following statements about reaction intermediates is correct?

Accepted Answer

Intermediates are formed and consumed during the reaction mechanism.

Question 17

In a reaction coordinate diagram, what does the highest point between reactants and products represent?

Accepted Answer

The transition state

Question 18

For a reaction where $$\Delta n = (	ext{moles of gaseous products}) - (	ext{moles of gaseous reactants})$$, how is the equilibrium constant $$K_p$$ related to $$K_c$$?

Accepted Answer

$$K_p = K_c (RT$$)^{\Delta n}$$

Question 19

Which of the following is true about the effect of a catalyst on the equilibrium position of a chemical reaction?

Accepted Answer

A catalyst does not affect the equilibrium position.

Chemical Kinetics and Equilibrium: Mechanisms, Rate Laws, and Catalysis

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