Calculate Kp for the reaction H2 (g) + I2 (g) ⇄ 2HI (g) at 25°C

Calculate K_p for the below reaction at 25°C:

Solution:

Interpretation: We will use the equation that describes the relation between equilibrium constant (K_p ) and Gibb’s free energy change (ΔG°).

ΔG° = – RTlnK_p

Where, ΔG° = Standard free energy change

K_p = Equilibrium constant in terms of pressure

Given: ΔG° = 2.60 kJ/mol

Solution: ΔG° = – RTlnK_p

Therefore, K_p for the reaction, H₂ (g) + I₂ (g) ⇄ 2HI (g) is 0.35 .