Question

For the following reaction at 298 K: \[ \text{30O}_2(g) \rightleftharpoons \text{20O}_3(g) \quad \Delta H = +285 \, \text{kJ/mol} \] The equilibrium constant, \( K_c \), is \[ K_c = 2.47 \times 10^{-31} \quad \text{at 298 K. The value of \( K_c \) will increase when} 298 \, \text{K is} \quad \text{increased.} \]

• A. Temperature is increased and pressure is decreased.
• B. Temperature is decreased and pressure is increased.
• C. Temperature is decreased and pressure is decreased.
• D. Temperature and pressure both are increased.

Hint:

For reactions with positive \( \Delta H \), increasing temperature will increase the equilibrium constant, and increasing pressure shifts the reaction towards fewer moles of gas.

Answer 1

The Correct Option is D

For a reaction with a positive enthalpy change (\( \Delta H = +285 \, \text{kJ/mol} \)), the equilibrium constant \( K_c \) increases with an increase in temperature. This is because an increase in temperature shifts the reaction towards the product side (exothermic). Additionally, according to Le Chatelier's principle, increasing the pressure will also shift the reaction towards fewer moles of gas. In this case, the reaction shifts to the right with increased pressure and temperature.