Question 1

Which of the following best describes the activation energy ($$E_a) in a $$chemical reaction?

Accepted Answer

The minimum amount of energy required to break the bonds between atoms of the reactants.

Question 2

For the reaction $$2CO(g) + O_2$(g) \rightarrow 2CO_2(g)$$, which of the following changes will increase the rate of reaction?

Accepted Answer

Adding a catalyst.

Question 3

Which of the following statements about chemical equilibrium is correct?

Accepted Answer

At equilibrium, the concentrations of reactants and products no longer change with time.

Question 4

Consider the reaction $$N_2(g$$) + $$O_2(g$$) \rightarrow 2NO(g)$$. According to collision theory, which of the following is NOT required for this reaction to occur?

Accepted Answer

Reactant molecules must be in the liquid phase.

Question 5

Which of the following energy diagrams represents an endothermic reaction?

Accepted Answer

The products are at a higher energy level than the reactants.

Question 6

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

Accepted Answer

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

Question 7

For the reaction $$H_2(g$$) + $$I_2(g$$) \rightleftharpoons 2HI(g)$$, which of the following is the correct equilibrium constant expression (K_c$)?

Accepted Answer

$$K_c = \dfrac{[HI]^2}{[H_2$][I_2$]}$$

Question 8

A reaction mixture at equilibrium contains $$[N_2O_4] = 0.45\ M$$ and $$[NO_2$] = 0.31\ M$$ for the reaction $$N_2O_4(g) \rightleftharpoons 2NO_2(g). $$What is the value of $$K_c$$?

Accepted Answer

$$K_c = \dfrac{(0.31)^2$}{0.45} = 0.21$$

Question 9

Which of the following actions will shift the equilibrium to the right (toward products) for the reaction $$CO_2(g$$) + $$H_2(g$$) \rightleftharpoons CO(g) + H_2O(g)$$?

Accepted Answer

Removing $$CO$$

Question 10

For the reaction $$2NO_2(g) \rightleftharpoons 2NO(g) + O_2$(g)$$, which of the following will shift the equilibrium toward the reactants?

Accepted Answer

Decreasing the temperature (the reaction is endothermic).

Question 11

Which of the following statements about catalysts is TRUE?

Accepted Answer

A catalyst lowers the activation energy for both the forward and reverse reactions.

Question 12

For the reaction $$3O_2(g) \rightleftharpoons 2O_3(g)$$, what is the correct equilibrium constant expression ($$K_c$$)?

Accepted Answer

$$K_c = \dfrac{[O_3$]^2}{[O_2$]^3}$$

Question 13

A reaction has a very large equilibrium constant ($$K_c \gg 1). $$What does this indicate about the equilibrium mixture?

Accepted Answer

The mixture contains mostly products.

Question 14

Which of the following will NOT affect the position of equilibrium for a gaseous reaction?

Accepted Answer

Adding a catalyst.

Question 15

For the reaction $$H_2(g$$) + $$I_2(g$$) \rightleftharpoons 2HI(g)$$, what will happen if the temperature is increased, given that the reaction is endothermic?

Accepted Answer

The equilibrium will shift toward the products.

Question 16

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

Accepted Answer

It increases the number of collisions with sufficient energy.

Question 17

A reaction mixture contains $$[CO_2$] = 0.25\ M$$, $$[H_2$] = 0.80\ M$$, $$[H_2O] = 0.50\ M$$, and $$K_c = 0.11$$ for the reaction $$CO_2(g$$) + $$H_2(g$$) \rightleftharpoons CO(g) + H_2O(g)$$. What is the equilibrium concentration of CO$?

Accepted Answer

$$[CO] = 0.11 	imes \dfrac{0.25 	imes 0.80}{0.50} = 0.044\ M$$

Question 18

Which of the following changes will shift the equilibrium toward the reactants for the exothermic reaction $$2SO_2(g) + O_2$(g) ightleftharpoons 2SO_3(g) + 	ext{heat}$$?

Accepted Answer

Increasing the temperature.

Question 19

Which of the following is TRUE about reversible reactions at equilibrium?

Accepted Answer

The rates of the forward and reverse reactions are equal.

Chapter 10 – Reaction Rates and Chemical Equilibrium: Study Notes

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