Question

Calculate ΔG for the reaction at 25°C

CO_(g) + 2H_2(g) ⇌ CH₃OH_(g)

ΔG⁰ = -24.8 kJ mol^-1.

If P_co = 4 atm, P_H2  = 2 atm, P_CH3OH = 2 atm.

Answer 1

Given : 

Partial pressures : pco = 4 atm,

P_H2 = 2 atm,

P_CH3OH = 2 atm

Temperature = T = 273 + 25 = 298 K

ΔG⁰ = -24.8 kJ mol^-1

CO_(g) + 2H_2(g) ⇌ CH₃OH_(g)

The reaction quotient, Q is,

= – 24.8 + 2.303 × 8.314 × 298 × log₁₀0.125

= – 24.8 + 2.303 × 8.314 × 298 × (\(\bar1.09691\))

= – 24.8 + 2.303 × 8.314 × 298 × (- 0.90709)

= – 24.8 – 2.303 × 8.314 × 298 × 0.90709 × 10^-3

= -24.8 – 5.176

= -29.976 kJ mol^-1

∴ ΔG = – 29.976 kJ mol^-1