Question 1

Which of the following best describes the meaning of a small equilibrium constant ($$K \ll 1) $$for the reaction $$\mathrm{N_2$(g) + O_2$(g) \rightleftharpoons 2\ NO(g)} as $$shown in the first image?

Accepted Answer

The reaction mixture at equilibrium contains mostly reactants.

Question 2

For the reaction $$\mathrm{H_2$(g) + Br_2$(g) \rightleftharpoons 2\ HBr(g)}$$, the equilibrium constant $$K is $$large. What does this indicate about the equilibrium concentrations?

Accepted Answer

The equilibrium mixture contains mostly $$\mathrm{HBr}.$$

Question 3

Given the equilibrium $$\mathrm{A(g) \rightleftharpoons B(g)}$$, the three boxes in the third image represent equilibrium mixtures at three different temperatures. If the number of red spheres (B) increases from $$T_1 to$$ $$T_3$$, what can you conclude about the effect of temperature on the equilibrium constant $$K$$?

Accepted Answer

$$K$$ increases as temperature increases.

Question 4

For the reaction $$\mathrm{N_2$(g) + O_2$(g) \rightleftharpoons 2\ NO(g)}$$, which of the following expressions correctly represents the equilibrium constant $$K$$?

Accepted Answer

$$K = \dfrac{[NO]^2}{[N_2$][O_2$]}$$

Question 5

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

Accepted Answer

The reaction favors the formation of products at equilibrium.

Question 6

Consider the reaction $$\mathrm{H_2$(g) + Br_2$(g) \rightleftharpoons 2\ HBr(g)}. If $$the equilibrium mixture contains 0.10 M $$\mathrm{H_2$}$$, 0.10 M $$\mathrm{Br_2$}$$, and 1.0 M $$\mathrm{HBr}$$, what is the value of $$K$$?

Accepted Answer

$$K = \dfrac{(1.0)^2$}{(0.10)(0.10)} = 100$$

Question 7

Which of the following statements about dynamic equilibrium is correct?

Accepted Answer

At equilibrium, the rates of the forward and reverse reactions are equal.

Question 8

For the reaction $$\mathrm{N_2$(g) + O_2$(g) \rightleftharpoons 2\ NO(g)}$$, what would happen to the value of $$K if $$the equation is reversed?

Accepted Answer

The new $$K is $$the reciprocal of the original $$K.$$

Question 9

If the equation $$\mathrm{N_2$(g) + O_2$(g) \rightleftharpoons 2\ NO(g)} is $$multiplied by 2, how does the equilibrium constant change?

Accepted Answer

The new $$K is $$the square of the original $$K.$$

Question 10

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

Accepted Answer

Their concentrations are constant and do not change during the reaction.

Question 11

For the reaction $$\mathrm{H_2$(g) + I_2$(g) \rightleftharpoons 2\ HI(g)}$$, which of the following is true at equilibrium?

Accepted Answer

The rate of the forward reaction equals the rate of the reverse reaction.

Question 12

If two reactions are added together, how is the equilibrium constant for the overall reaction related to the equilibrium constants of the individual reactions?

Accepted Answer

The overall $$K is $$the product of the individual $$K$$ values.

Question 13

For the reaction $$\mathrm{N_2$(g) + O_2$(g) \rightleftharpoons 2\ NO(g)}$$, if the equilibrium constant $$K is $$very small, which of the following is most likely true about the mixture at equilibrium?

Accepted Answer

There will be much more $$\mathrm{N_2$}$$ and $$\mathrm{O_2$}$$ than $$\mathrm{NO}.$$

Question 14

Which of the following is the correct relationship between $$K_p$$ and $$K_c$$ for a reaction involving gases?

Accepted Answer

$$K_p = K_c(RT$$)^{\Delta n}$$

Question 15

For the reaction $$\mathrm{2\ NO(g) + O_2$(g) ightleftharpoons 2\ NO_2$(g)}$$, if $$K_p = 2.2 	imes 10$$^{12}$$ at 25$$^\circ$$C$$, what is $$\Delta n$ for this reaction?

Accepted Answer

$$\Delta n = -1$$

Chemical Equilibrium: Principles and the Equilibrium Constant

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