Question 1

The equilibrium constant, $$K$$, for a reaction is defined as the ratio of the concentrations of which of the following at equilibrium?

Accepted Answer

Products to reactants

Question 2

For the reaction $$2 	ext{NO}_2 (g) ightleftharpoons 2 	ext{NO} (g) + 	ext{O}_2 (g)$$, the equilibrium constant $$K is$$ $$6.9 	imes 10^2$. If the concentrations at equilibrium are $$[	ext{NO}] = 1.5 	imes $$10^{-2}$$ 	ext{M}$$, $$[	ext{O}_2] = 4.3 	imes $$10^{-3}$$ 	ext{M}$$, and $$[	ext{NO}_2] = x$$, what is the value of x$?

Accepted Answer

$$x = 2.2 	imes 10$$^{-2}$$

Question 3

If the equilibrium constant $$K$$ for a reaction is much greater than 1, which of the following statements is true?

Accepted Answer

Products are favored at equilibrium

Question 4

Given the reaction $$N_2 (g$$) + $$O_2 (g$$) ightleftharpoons 2 NO (g)$$ and K = 1.0$$ 	imes $$10^{-5}$$, which is present in greater amount at equilibrium?

Accepted Answer

$$N_2 (g) $$and $$O_2 (g)$$

Question 5

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

Accepted Answer

Solids

Question 6

For the reaction $$2 SO_2$ (g) + O_2$ (g) \rightleftharpoons 2 SO_3$ (g)$$, write the correct equilibrium constant expression.

Accepted Answer

$$K = \frac{[SO_3$]^2}{[SO_2$]^2 [O_2$]}$$

Question 7

A reaction has $$K = 1. $$What does this indicate about the concentrations of reactants and products at equilibrium?

Accepted Answer

Reactants and products are present in roughly equal amounts

Question 8

For the reaction $$2 BrCl (g) \rightleftharpoons Br_2$ (g) + Cl_2$ (g)$$ with $$K = 1$$, which statement is correct?

Accepted Answer

All species are present in comparable amounts

Question 9

If the equilibrium constant for a reaction is very small, which direction is favored?

Accepted Answer

Reverse (reactants)

Question 10

Which of the following would increase the value of the equilibrium constant $$K$$ for an exothermic reaction?

Accepted Answer

Decreasing the temperature

Question 11

For the reaction $$6 NO (aq) \rightleftharpoons 3 N_2$ (aq) + 3 O_2$ (aq)$$, what is the equilibrium constant expression?

Accepted Answer

$$K = \frac{[N_2$]^3 [O_2$]^3}{[NO]^6}$$

Question 12

A student writes the equilibrium expression for $$2 Fe$$^{3+}$$ (aq) + 3 I^- (aq) \rightleftharpoons 2 Fe$$^{2+}$$ (aq) + I_3$^- (aq) as$$ $$K = \frac{[Fe$$^{3+}$$]^2 [I^-]^3}{[Fe$$^{2+}$$]^2 [I_3$^-]}. $$What is the error?

Accepted Answer

The numerator and denominator are reversed

Question 13

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

Accepted Answer

Adding a catalyst

Question 14

In a closed system at equilibrium, which of the following is true?

Accepted Answer

The rates of the forward and reverse reactions are equal

Question 15

For the reaction $$2 NO_2$ (g) ightleftharpoons 2 NO (g) + O_2$ (g)$$, if $$K = 6.9 	imes 10^2$, which is favored at equilibrium?

Accepted Answer

NO (g) and $$O_2 (g)$$

Question 16

A reaction mixture initially contains only reactants. As the reaction proceeds toward equilibrium, what happens to the value of $$K$$?

Accepted Answer

$$K$$ remains constant

Chemical Equilibrium and the Equilibrium Constant (K)

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