Question 1

Which of the following best describes chemical equilibrium in a closed system?

Accepted Answer

The rates of the forward and reverse reactions are equal.

Question 2

For the reaction $$\mathrm{N_2O_4(g) \rightleftharpoons 2NO_2(g)}$$, if $$[\mathrm{N_2O_4}] = 0.055\ \mathrm{M}$$ and $$[\mathrm{NO_2$}] = 0.060\ \mathrm{M}$$, what is the equilibrium constant $$K$$?

Accepted Answer

$$K = 0.065$$

Question 3

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

Accepted Answer

It changes with temperature.

Question 4

Given the reaction $$\mathrm{$$TiCl_4$$(g) + O_2$(g) \rightleftharpoons $$TiO_2$$(s) + 2Cl_2(g)}$$, what is the correct equilibrium constant expression?

Accepted Answer

$$K = \dfrac{[\mathrm{Cl_2$}]^2}{[\mathrm{$$TiCl_4$$}][\mathrm{O_2$}]}$$

Question 5

Which of the following changes will NOT affect the position of a heterogeneous equilibrium?

Accepted Answer

Adding more pure solid reactant.

Question 6

For the reaction $$\mathrm{2A(g) + B(g) \rightleftharpoons 3C(g)}$$, if $$[A] = 0.30\ \mathrm{M}$$, $$[B] = 0.20\ \mathrm{M}$$, and $$K = 23$$, what is the equilibrium concentration of $$C$$?

Accepted Answer

$$[C] = 0.75\ \mathrm{M}$$

Question 7

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

Accepted Answer

The reaction mixture contains mostly products.

Question 8

Consider the equilibrium $$\mathrm{C(s) + H_2O(g) + heat \rightleftharpoons CO(g) + H_2$(g)}. If$$ $$H_2(g$$)$$ is added to the system, what will happen to $$[CO]$$ and K$$_{eq}$$?

Accepted Answer

$$[CO]$$ decreases, $$K_{eq}$$ remains the same

Question 9

For the reaction $$\mathrm{2KClO_3(s) \rightleftharpoons 2KCl(s) + 3O_2(g)}$$, what is the correct equilibrium constant expression?

Accepted Answer

$$K = [\mathrm{O_2$}]^3$$

Question 10

A student observes a system: $$\mathrm{2A(g) + B(g) \rightleftharpoons 3C(g)}$$ with $$K = 23. If$$ $$[A] = 0.48\ \mathrm{M}$$, $$[B] = 0.38\ \mathrm{M}$$, and $$[C] = 0.18\ \mathrm{M}$$, what is the value of $$Q$$ and which way will the reaction shift to reach equilibrium?

Accepted Answer

$$Q = 0.067$$, shift right

Question 11

Which of the following stresses will cause the equilibrium position of $$\mathrm{N_2$(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)} to $$shift to the right?

Accepted Answer

Removing $$\mathrm{NH_3$}$$

Question 12

For the dissociation of acetic acid $$\mathrm{HC_2H_3O_2(aq) \rightleftharpoons H^+(aq) + C_2H_3O_2^-(aq)}$$, what is the correct equilibrium constant expression?

Accepted Answer

$$K = \dfrac{[\mathrm{H}^+][\mathrm{C_2H_3O_2}^-]}{[\mathrm{HC_2H_3O_2}]}$$

Question 13

Which of the following statements about the reaction quotient $$Q is $$correct?

Accepted Answer

$$Q is $$calculated the same way as $$K$$ but with any set of concentrations.

Question 14

If the temperature is increased for an endothermic reaction at equilibrium, what will happen to the value of $$K$$?

Accepted Answer

$$K$$ increases

Question 15

For the reaction $$\mathrm{$$CaF_2$$(s) \rightleftharpoons Ca$$^{2+}$$(aq) + 2F^-(aq)}$$, what is the correct equilibrium constant expression?

Accepted Answer

$$K = [\mathrm{Ca}^{2+}][\mathrm{F}^-]^2$$

Question 16

Which of the following best explains why the concentrations of pure solids and liquids are omitted from equilibrium constant expressions?

Accepted Answer

Their concentrations do not change during the reaction.

Question 17

A reaction mixture is at equilibrium. If the volume of the container is decreased, what will happen to the equilibrium position for a reaction where the number of moles of gas decreases from reactants to products?

Accepted Answer

The equilibrium will shift toward the products.

Chemical Equilibrium: Principles, Expressions, and Effects of Changes

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