Question 1

Which of the following statements best describes the effect of a catalyst on a chemical reaction at equilibrium?

Accepted Answer

It lowers the activation energy, allowing equilibrium to be reached faster, but does not change the equilibrium concentrations.

Question 2

For the reaction $$\mathrm{N_2$(g) + O_2$(g) \rightarrow 2NO(g)}$$, which of the following must be true for the reaction to occur according to collision theory?

Accepted Answer

Reactant molecules must collide with sufficient energy and proper orientation.

Question 3

Which of the following energy diagrams represents an endothermic reaction?

Accepted Answer

A diagram where the products have higher energy than the reactants.

Question 4

Consider the reaction $$2CO(g) + O_2$(g) \rightarrow 2CO_2(g). $$What effect does increasing the concentration of $$CO(g)$$ have on the rate of reaction?

Accepted Answer

It increases the rate of reaction by causing more frequent collisions.

Question 5

For the reaction $$H_2(g$$) + $$I_2(g$$) \rightleftharpoons 2HI(g)$$, which of the following is true at equilibrium?

Accepted Answer

The rate of the forward reaction equals the rate of the reverse reaction.

Question 6

Which of the following changes will shift the equilibrium of $$N_2O_4(g) \rightleftharpoons 2NO_2(g)$$ toward the products?

Accepted Answer

Adding $$N_2O_4$$

Question 7

Given the reaction $$2CO(g) + O_2$(g) \rightleftharpoons 2CO_2(g)$$, write the equilibrium constant expression $$K_c.$$

Accepted Answer

$$K_c = \dfrac{[CO_2$]^2}{[CO]^2[O_2$]}$$

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

For the reaction $$CO_2(g$$) + $$H_2(g$$) \rightleftharpoons CO(g) + H_2O(g)$$, the equilibrium concentrations are $$[$$CO_2$$] = 0.175\,M$$, $$[$$H_2$$] = 0.0274\,M$$, $$[CO] = 0.0233\,M$$, and $$[H_2O] = 0.0115\,M$$. What is the value of K_c$?

Accepted Answer

$$K_c = \dfrac{[CO][H_2O]}{[CO_2$][H_2$]} = \dfrac{(0.0233)(0.0115)}{(0.175)(0.0274)} = 0.056$$

Question 10

If the equilibrium constant $$K_c$$ for a reaction is much greater than 1, what does this indicate about the equilibrium mixture?

Accepted Answer

The mixture contains mostly products.

Question 11

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

Accepted Answer

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

Question 12

Which of the following changes will shift the equilibrium of $$2SO_2(g) + O_2$(g) \rightleftharpoons 2SO_3(g)$$ toward the reactants?

Accepted Answer

Removing $$SO_2$$

Question 13

Consider the endothermic reaction $$N_2(g$$) + $$O_2(g$$) + 	ext{heat} ightleftharpoons 2NO(g)$$. What will happen if the temperature is increased?

Accepted Answer

The equilibrium will shift toward the products.

Question 14

For the reaction $$2CO(g) + O_2$(g) \rightleftharpoons 2CO_2(g)$$, what effect does decreasing the volume of the reaction vessel have on the equilibrium?

Accepted Answer

It shifts the equilibrium toward the side with fewer moles of gas (products).

Question 15

Which of the following is NOT a factor that affects the rate of a chemical reaction?

Accepted Answer

Concentration of products

Question 16

For the reaction $$H_2(g$$) + $$I_2(g$$) \rightleftharpoons 2HI(g)$$, what will happen if more HI$ is added to the system at equilibrium?

Accepted Answer

The equilibrium will shift toward the reactants.

Question 17

Which of the following best explains why reaction rates generally decrease as a reaction proceeds?

Accepted Answer

The concentration of reactants decreases, leading to fewer collisions.

Question 18

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

Accepted Answer

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

Chapter 10 – Reaction Rates and Chemical Equilibrium: Study Notes

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