Question 1

Which statement best describes dynamic equilibrium in a chemical reaction?

Accepted Answer

The rates of the forward and reverse reactions are equal.

Question 2

For the reaction $$\mathrm{H_2$(g) + I_2$(g) \rightleftharpoons 2HI(g)}$$, what happens to the concentrations of $$\mathrm{H_2$}$$, $$\mathrm{I_2$}$$, and $$\mathrm{HI} as $$the system approaches equilibrium?

Accepted Answer

The concentrations of $$\mathrm{H_2$}$$ and $$\mathrm{I_2$}$$ decrease, while $$\mathrm{HI}$$ increases.

Question 3

Which of the following is true about the equilibrium constant $$K$$ for a reaction?

Accepted Answer

It is unitless and depends only on temperature.

Question 4

Consider the reaction $$\mathrm{2N_2O_5(g) \rightleftharpoons 4NO_2(g) + O_2$(g)}. $$What is the correct equilibrium constant expression?

Accepted Answer

$$K = \dfrac{[NO_2$]^4[O_2$]}{[N_2O_5]^2}$$

Question 5

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

Accepted Answer

The reaction favors the products.

Question 6

For the reaction $$\mathrm{A(g) \rightleftharpoons 2B(g)}$$ with $$K = 0.010$$, what is the equilibrium constant for $$\mathrm{B(g) \rightleftharpoons \frac{1}{2}A(g)}$$?

Accepted Answer

$$K = 100$$

Question 7

Which of the following changes will NOT affect the value of the equilibrium constant $$K$$ for a reaction?

Accepted Answer

Adding a catalyst.

Question 8

For the reaction $$\mathrm{$$CaCO_3$$(s) \rightleftharpoons CaO(s) + CO_2$(g)}$$, which species are included in the equilibrium constant expression?

Accepted Answer

Only $$\mathrm{CO_2$(g)}$$

Question 9

A reaction mixture initially contains $$[CO] = 0.50\ \mathrm{M}$$ and $$[H_2$] = 1.00\ \mathrm{M}. At $$equilibrium, $$[CO] = 0.15\ \mathrm{M}. $$For $$\mathrm{CO(g) + 2H_2(g) \rightleftharpoons CH_3OH(g)}$$, what is the equilibrium concentration of $$\mathrm{CH_3OH}$$?

Accepted Answer

$$0.35\ \mathrm{M}$$

Question 10

Which statement about the reaction quotient $$Q is $$correct?

Accepted Answer

It is calculated using concentrations at any point in the reaction.

Question 11

If $$Q \u003c K$$ for a reaction mixture, what will happen as the system moves toward equilibrium?

Accepted Answer

The reaction will shift toward the products.

Question 12

For the reaction $$\mathrm{N_2$(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)}$$, what will happen if more $$\mathrm{H_2$} is $$added to a system at equilibrium?

Accepted Answer

The equilibrium will shift toward the products.

Question 13

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

Accepted Answer

Adding an inert gas at constant volume.

Question 14

For the reaction $$\mathrm{N_2$(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)}$$, what is the effect of increasing the temperature?

Accepted Answer

The equilibrium shifts toward the reactants and $$K$$ decreases.

Question 15

For an endothermic reaction, what is the effect of decreasing the temperature?

Accepted Answer

The equilibrium shifts toward the reactants and $$K$$ decreases.

Question 16

A catalyst is added to a reaction at equilibrium. What is the effect?

Accepted Answer

The time to reach equilibrium decreases, but the position of equilibrium does not change.

Question 17

For the reaction $$\mathrm{2SO_2(g) + O_2$(g) \rightleftharpoons 2SO_3(g)}$$, what will happen if the volume of the container is decreased?

Accepted Answer

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

Question 18

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

Accepted Answer

Only the concentrations of gases and aqueous species are included in the equilibrium constant expression.

Chemical Equilibrium: Principles and Applications

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