Question

For the following reactions, equilibrium constants are given:

S (s) + O (g) ⇌ SO₂ (g); K₁ = 10⁵²

2S (s) + 3O₂ (g) ⇌ 2SO₃ (g); K₂ = 10¹²⁹

The equilibrium constant for the reaction,

2SO₂ (g) + O₂ (g) ⇌ 2SO₃ (g) is;
1. 10¹⁵⁴
2. 10¹⁸¹
3. 10²⁵
4. 10⁷⁷

Answer 1

Correct Answer - Option 3 : 10²⁵

Concept:

Given reactions,

S (s) + O (g) ⇌ SO₂ (g); K₁ = 10⁵²        ----(1)

2S (s) + 3O₂ (g) ⇌ 2SO₃ (g); K₂ = 10¹²⁹        ----(2)       

We need to find equilibrium constant (K) for the reaction 2SO₂ + O₂ ⇌ 2SO₃

To find K, follow (2) – 2 × (1)

Equation (1) ⇒ 2s + 3O₂ → 2SO₃; K = 10¹²⁹

Equation (2) ⇒ - 2S + 2SO₂ → 2SO₂; K = 10¹⁰⁴

By using cancellation law, we get,

O₂ → 2S₃ – 2SO₂; K = 10²⁵