Question

For the reaction,

2SO₂ (g) + O₂ (g) ⇌ 2SO₃ (g)

ΔH = -57.2 kJmol^-1 and K_c = 1.7 × 10¹⁶

Which of the following statement is INCORRECT?
1. The equilibrium constant is large suggestive of reaction going to completion and so no catalyst is required.
2. The equilibrium will shift in forward direction as the pressure increases.
3. The equilibrium constant decreases as the temperature increases.
4. The addition of inert gas at constant volume will not affect the equilibrium constant.

Answer 1

Correct Answer - Option 1 : The equilibrium constant is large suggestive of reaction going to completion and so no catalyst is required.

Concept:

In option (a):

Delta ng of an equation = number of gaseous molecules of products – number of gaseous molecules of reactants.

Δng = n₁ – n₂

From reaction,

⇒ Δng = 2 – 3 = - 1

Δn_g is negative therefore increase in pressure will bring reaction in forward direction.

In option (c):

As the reaction is exothermic, therefore increase in temperature will decrease the equilibrium constant.

In option (d):

When an inert gas is added to the system in equilibrium at constant volume, the total pressure will increase. But the concentrations of the products and reactants (i.e. ratio of their moles to the volume of the container) will not change.

In option (a):

The equilibrium constant is a mathematical relationship that shows how the concentrations of the products vary with the concentration of the reactants.

Hence, option (b), (c) and (d) are correct therefore option (a) is the incorrect choice.