Eduprobe
Question:
For the reaction 2SO2(g) + O2(g)⇌2SO3(g), ΔH = −57.2 kJ mol⁻¹; and Kc = 1.7 × 10¹⁶. Which of the following statement is INCORRECT?
The equilibrium constant is large suggestive of reaction going to completion and so no catalyst is required
The addition of inert gas at constant volume will not affect the equilibrium constant
The equilibrium will shift in forward direction as the pressure increase
The equilibrium constant decreases as the temperature increases
Solution:
In option (B): Δng is -ve, therefore, the increase in pressure will bring the reaction in the forward direction. The equilibrium constant is large (Kc = 1.7 × 10¹⁶), indicating that the reaction proceeds almost to completion. However, this does not mean a catalyst is unnecessary. A catalyst speeds up the rate of the reaction, allowing equilibrium to be reached faster. The addition of an inert gas at constant volume does not change the partial pressures of the reactants or products, therefore it does not affect the equilibrium constant. Increasing the pressure shifts the equilibrium towards the side with fewer moles of gas (Le Chatelier's principle). Since there are 3 moles of gas on the reactant side and 2 moles on the product side, increasing the pressure shifts the equilibrium towards the products (forward direction). The reaction is exothermic (ΔH = -57.2 kJ mol⁻¹), meaning heat is released. According to Le Chatelier's principle, increasing the temperature will shift the equilibrium to the left (towards reactants), thus decreasing the equilibrium constant.