Kc and Kp Knowledge-Based Download PDF

Questions

1. 1.

   For the gas-phase reaction $2\text{SO}_3(g) \rightleftharpoons 2\text{SO}_2(g) + \text{O}_2(g)$, the equilibrium constants are $K_c = 0.040$ and $K_p = 0.984$ at temperature $T$. What is the value of $T$ in kelvins? (Take $R = 0.082\text{ L}\cdot\text{atm}\cdot\text{mol}^{-1}\cdot\text{K}^{-1}$)

   • A) 300 K
   • B) 600 K
   • C) 150 K
   • D) 246 K
2. 2.

   For the heterogeneous equilibrium reaction $\text{NH}_4\text{HS}(s) \rightleftharpoons \text{NH}_3(g) + \text{H}_2\text{S}(g)$, what is the value of the exponent $\Delta n$ in the relationship $K_p = K_c(RT)^{\Delta n}$?

   • A) -1
   • B) 1
   • C) 2
   • D) 0
3. 3.

   Which of the following statements is correct regarding the relationship between the equilibrium constants $K_c$ and $K_p$ for a reversible reaction?

   • A) The exponent $\Delta n$ is calculated as the sum of stoichiometric coefficients of gaseous reactants minus that of gaseous products.
   • B) Stoichiometric coefficients of pure solids and pure liquids must be included when determining $\Delta n$.
   • C) The numerical values of $K_p$ and $K_c$ can never be equal because pressure and molar concentration are expressed in different units.
   • D) The numerical values of $K_p$ and $K_c$ are equal at any temperature whenever the stoichiometric sum of gaseous products equals that of gaseous reactants.
4. 4.

   At 500 K, the concentration equilibrium constant $K_c$ for the reaction $\text{N}_2(g) + 3\text{H}_2(g) \rightleftharpoons 2\text{NH}_3(g)$ is equal to 0.50. Which of the following expressions represents the numerical value of the pressure equilibrium constant $K_p$ for this reaction at the same temperature?

   • A) $0.50 \times (500R)^2$
   • B) $\frac{0.50}{500R}$
   • C) $\frac{0.50}{(500R)^2}$
   • D) $0.50 \times (500R)$
5. 5.

   For which of the following equilibrium reactions is the relationship between the equilibrium constants represented by $K_p = K_c(RT)^{-1}$?

   • A) $2\text{SO}_2(g) + \text{O}_2(g) \rightleftharpoons 2\text{SO}_3(g)$
   • B) $\text{N}_2\text{O}_4(g) \rightleftharpoons 2\text{NO}_2(g)$
   • C) $\text{H}_2(g) + \text{I}_2(g) \rightleftharpoons 2\text{HI}(g)$
   • D) $\text{C}(s) + \text{CO}_2(g) \rightleftharpoons 2\text{CO}(g)$