Question 1

Which of the following best describes dynamic equilibrium in a chemical reaction?

Accepted Answer

The rate of the forward reaction equals the rate of the reverse reaction, and concentrations remain constant.

Question 2

For the reaction $$\mathrm{N_2O_4(g) \rightleftharpoons 2NO_2(g)}$$, what will happen if more $$\mathrm{NO_2$} is $$added to the system at equilibrium?

Accepted Answer

The reaction will shift left, producing more $$\mathrm{N_2O_4}.$$

Question 3

Which of the following changes will increase the rate of a chemical reaction according to collision theory?

Accepted Answer

Increasing the concentration of reactants.

Question 4

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

Accepted Answer

$$K_{eq} = \frac{[C]^c [D]^d}{[A]^a [B]^b}$$

Question 5

A reaction has a very large equilibrium constant ($$K_{eq} \gg 1). $$What does this imply about the reaction at equilibrium?

Accepted Answer

The concentration of products is much higher than reactants.

Question 6

For the dissolution of $$\mathrm{$$CaF_2$$(s) \rightleftharpoons Ca$$^{2+}$$(aq) + 2F^-(aq)}$$, what is the correct expression for the solubility product constant ($$K_{sp}$$)?

Accepted Answer

$$K_{sp} = [Ca$$^{2+}$$][F^-]^2$$

Question 7

If the volume of a container holding the equilibrium mixture $$\mathrm{N_2$(g) + 3H_2(g) \rightleftharpoons 2NH_3(g)} is $$decreased, what will happen to the position of equilibrium?

Accepted Answer

It will shift to the right, toward fewer moles of gas.

Question 8

Which of the following statements about catalysts is correct?

Accepted Answer

A catalyst lowers the activation energy and speeds up the reaction.

Question 9

For the reaction $$\mathrm{N_2O_4(g) \rightleftharpoons 2NO_2(g)}$$, which of the following will shift the equilibrium to the right?

Accepted Answer

Adding $$\mathrm{N_2O_4}.$$

Question 10

A reaction is exothermic. What will happen to the equilibrium position if the temperature is increased?

Accepted Answer

The equilibrium will shift to the left.

Question 11

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

Accepted Answer

It increases the number of high-energy collisions between molecules.

Question 12

A mixture of $$\mathrm{H_2$}$$ and $$\mathrm{I_2$} at $$equilibrium at 445°C has $$[H_2$] = 0.11\ M$$, $$[I_2$] = 0.11\ M$$, and $$[HI] = 0.78\ M. $$What is the value of $$K_{eq}$$ for $$\mathrm{H_2$(g) + I_2$(g) \rightleftharpoons 2HI(g)}$$?

Accepted Answer

$$K_{eq} = \frac{[HI]^2}{[H_2$][I_2$]} = \frac{(0.78)^2$}{(0.11)(0.11)} = 50$$

Question 13

Which of the following is NOT included in the equilibrium constant expression for a heterogeneous equilibrium?

Accepted Answer

Pure solids

Question 14

Le Châtelier’s Principle can be used to explain which of the following real-life scenarios?

Accepted Answer

Why increasing the pressure in a soda bottle keeps more carbon dioxide dissolved.

Question 15

Fetal hemoglobin has a larger equilibrium constant for binding oxygen than adult hemoglobin. What is the physiological significance of this?

Accepted Answer

Fetal hemoglobin can load oxygen at lower oxygen concentrations, allowing oxygen transfer from mother to fetus.

Question 16

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

Accepted Answer

Adding a catalyst.

Question 17

For the reaction $$\mathrm{N_2O_4(g) + Heat \rightleftharpoons 2NO_2(g)}$$, what will happen if the temperature is decreased?

Accepted Answer

The equilibrium will shift to the left, producing more $$\mathrm{N_2O_4}.$$

Question 18

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

Accepted Answer

It provides an alternate pathway with a lower activation energy.

Question 19

Which of the following is the best definition of activation energy?

Accepted Answer

The energy required to break the bonds of the reactants and start the reaction.

Chemical Equilibrium: Principles, Expressions, and Applications

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