Equilibrium constant (K) Knowledge-Based Practice

Questions

1. 1.

   When two reversible chemical reactions with equilibrium constants $K_1$ and $K_2$ are added together to give an overall reaction at the same temperature, what is the equilibrium constant of the overall reaction?

   • A) $K_1 + K_2$
   • B) $K_1 / K_2$
   • C) $K_1 - K_2$
   • D) $K_1 \times K_2$
2. 2.

   Which of the following is the correct equilibrium constant expression, $K_c$, for the heterogeneous reaction $\text{Cu}(s) + 2\text{Ag}^+(aq) \rightleftharpoons \text{Cu}^{2+}(aq) + 2\text{Ag}(s)$?

   • A) $K_c = \frac{[\text{Cu}^{2+}][\text{Ag}]^2}{[\text{Cu}][\text{Ag}^+]^2}$
   • B) $K_c = \frac{[\text{Ag}^+]^2}{[\text{Cu}^{2+}]}$
   • C) $K_c = \frac{[\text{Cu}^{2+}]}{[\text{Ag}^+]}$
   • D) $K_c = \frac{[\text{Cu}^{2+}]}{[\text{Ag}^+]^2}$
3. 3.

   For which of the following reversible reactions does the equilibrium constant in terms of partial pressures, $K_p$, equal the equilibrium constant in terms of molar concentrations, $K_c$, at all temperatures?

   • A) $2\text{SO}_2(g) + \text{O}_2(g) \rightleftharpoons 2\text{SO}_3(g)$
   • B) $\text{PCl}_5(g) \rightleftharpoons \text{PCl}_3(g) + \text{Cl}_2(g)$
   • C) $\text{H}_2(g) + \text{I}_2(g) \rightleftharpoons 2\text{HI}(g)$
   • D) $\text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g)$
4. 4.

   Which of the following changes alters the numerical value of the equilibrium constant, $K_c$, for a reversible chemical reaction?

   • A) Adding a suitable catalyst to the reaction mixture
   • B) Increasing the initial concentration of the reactants
   • C) Decreasing the total volume of the reaction container
   • D) Changing the temperature of the reaction system
5. 5.

   At a given temperature, the equilibrium constant for the reaction $\text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g)$ is $K$. What is the equilibrium constant for the reaction $\text{NH}_3(g) \rightleftharpoons \frac{1}{2}\text{N}_2(g) + \frac{3}{2}\text{H}_2(g)$ at the same temperature?

   • A) $K^2$
   • B) $\frac{1}{\sqrt{K}}$
   • C) $-\frac{1}{2}K$
   • D) $\sqrt{K}$

Answers and step-by-step solutions appear after you finish the test.