Question 1

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

Accepted Answer

The rates of the forward and reverse reactions are equal, and the concentrations of reactants and products remain constant.

Question 2

Consider the equilibrium: $$\mathrm{Hb} + \mathrm{O}_2 \rightleftharpoons \mathrm{HbO}_2. $$What happens to the position of equilibrium when blood moves from the lungs (high $$[\mathrm{O}_2]) to $$the muscles (low $$[\mathrm{O}_2]$$)?

Accepted Answer

The equilibrium shifts to the right in the lungs and to the left in the muscles.

Question 3

For the reaction $$\mathrm{H}_2(g) + \mathrm{I}_2(g) \rightleftharpoons 2\mathrm{HI}(g)$$, which of the following is the correct expression for the equilibrium constant $$K_c$$?

Accepted Answer

$$K_c = \dfrac{[\mathrm{HI}]^2}{[\mathrm{H}_2][\mathrm{I}_2]}$$

Question 4

A reaction mixture initially contains only reactants. As the reaction proceeds toward equilibrium, what happens to the rates of the forward and reverse reactions?

Accepted Answer

The forward reaction rate decreases and the reverse reaction rate increases.

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 at equilibrium.

Question 6

For the reaction $$2\mathrm{CO}(g) \rightleftharpoons \mathrm{CO}_2(g) + \mathrm{C}(s)$$, which of the following statements is true regarding the equilibrium constant expression?

Accepted Answer

$$K_c = \dfrac{[\mathrm{CO}_2]}{[\mathrm{CO}]^2}$$

Question 7

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

Accepted Answer

Adding more reactant.

Question 8

For the reaction $$\mathrm{N}_2(g) + 3\mathrm{H}_2(g) \rightleftharpoons 2\mathrm{NH}_3(g)$$, what will happen to the position of equilibrium if the volume of the reaction vessel is decreased?

Accepted Answer

The equilibrium will shift to the right, favoring the formation of $$\mathrm{NH}_3.$$

Question 9

A reaction has $$K_c = 0.010$$ for $$\mathrm{A}(g) \rightleftharpoons 2\mathrm{B}(g). $$What is the equilibrium constant for $$\mathrm{B}(g) \rightleftharpoons \mathrm{A}(g$$)^{1/2}$$?

Accepted Answer

0.0010

Question 10

For the reaction $$\mathrm{A}(g) + \mathrm{B}(g) \rightleftharpoons \mathrm{C}(g) + \mathrm{D}(g)$$, which of the following is true if $$K_p = K_c$$?

Accepted Answer

The number of moles of gaseous reactants equals the number of moles of gaseous products.

Question 11

A mixture initially contains $$[\mathrm{A}] = 1.0\ \mathrm{M}$$ and $$[\mathrm{B}] = 0.0\ \mathrm{M}$$ for the reaction $$\mathrm{A}(g) \rightleftharpoons \mathrm{B}(g)$$ with $$K = 10. $$Which statement is true at equilibrium?

Accepted Answer

The reaction mixture contains $$[\mathrm{A}] = 0.1\ \mathrm{M}$$ and $$[\mathrm{B}] = 1.0\ \mathrm{M}.$$

Question 12

If $$Q \u003e K$$ for a reaction mixture, what will happen as the system moves toward equilibrium?

Accepted Answer

The reaction will proceed in the reverse direction, forming more reactants.

Question 13

Which of the following scenarios best illustrates Le Châtelier’s principle?

Accepted Answer

Adding more $$\mathrm{NO}_2 to $$the equilibrium $$\mathrm{N}_2\mathrm{O}_4(g) \rightleftharpoons 2\mathrm{NO}_2(g)$$ causes the system to shift left, forming more $$\mathrm{N}_2\mathrm{O}_4.$$

Question 14

For the exothermic reaction $$\mathrm{N}_2(g) + 3\mathrm{H}_2(g) ightleftharpoons 2\mathrm{NH}_3(g) + 	ext{heat}$$, what is the effect of increasing the temperature?

Accepted Answer

The equilibrium shifts to the left and $$K$$ decreases.

Question 15

A reaction mixture at equilibrium is disturbed by removing some product. What will happen according to Le Châtelier’s principle?

Accepted Answer

The reaction will shift to the right to produce more product.

Question 16

For the reaction $$\mathrm{A}(g) \rightleftharpoons \mathrm{B}(g)$$, $$K_c = 4.0. If$$ $$[\mathrm{A}] = 1.0\ \mathrm{M} at $$equilibrium, what is $$[\mathrm{B}]$$?

Accepted Answer

2.0 M

Question 17

Which of the following best explains why solids and pure liquids are not included in equilibrium constant expressions?

Accepted Answer

Their concentrations do not change during the reaction.

Question 18

For the endothermic reaction $$\mathrm{N}_2\mathrm{O}_4(g) + 	ext{heat} ightleftharpoons 2\mathrm{NO}_2(g)$$, what is the effect of increasing the temperature?

Accepted Answer

The equilibrium shifts to the right and $$K$$ increases.

Chemical Equilibrium: Principles, Expressions, and Applications

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