Equilibrium constant (K) Knowledge-Based Download PDF

Questions

1. 1.

   Under which of the following conditions is the numerical value of the partial pressure equilibrium constant, $K_p$, equal to the concentration equilibrium constant, $K_c$, for a reversible reaction involving gases?

   • A) When the total pressure of the equilibrium gas mixture is exactly 1 atm
   • B) When the activation energy of the forward step is identical to that of the reverse step
   • C) When the rate constant of the forward reaction equals the rate constant of the reverse reaction
   • D) When the sum of the stoichiometric coefficients of gaseous products equals the sum of the stoichiometric coefficients of gaseous reactants
2. 2.

   Which of the following statements correctly describes a reversible reaction that has a very large equilibrium constant, such that $K \gg 1$, at a given temperature?

   • A) At equilibrium, the rate of the forward reaction remains much greater than the rate of the reverse reaction.
   • B) At equilibrium, the reaction mixture contains predominantly products rather than reactants.
   • C) The reaction establishes dynamic equilibrium almost instantaneously upon mixing the reactants.
   • D) Introducing a suitable catalyst will significantly increase the final equilibrium yield of the products.
3. 3.

   At a given temperature, the equilibrium constant for the reaction $\text{PCl}_5(g) \rightleftharpoons \text{PCl}_3(g) + \text{Cl}_2(g)$ is $K$. What is the equilibrium constant for the reaction $2\text{PCl}_3(g) + 2\text{Cl}_2(g) \rightleftharpoons 2\text{PCl}_5(g)$ at the same temperature?

   • A) $-2K$
   • B) $\frac{2}{K}$
   • C) $\frac{1}{K^2}$
   • D) $K^2$
4. 4.

   Which of the following factors will alter the numerical value of the equilibrium constant, $K$, for a given reversible reaction?

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

   For the reversible reaction $\text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g)$, which expression correctly represents the equilibrium constant, $K_c$?

   • A) $K_c = \frac{[\text{NH}_3]^2}{[\text{N}_2][\text{H}_2]^3}$
   • B) $K_c = \frac{[\text{N}_2][\text{H}_2]^3}{[\text{NH}_3]^2}$
   • C) $K_c = \frac{2[\text{NH}_3]}{[\text{N}_2] + 3[\text{H}_2]}$
   • D) $K_c = \frac{[\text{NH}_3]}{[\text{N}_2][\text{H}_2]}$