Question

Calculate the standard Gibbs energy of the reaction CO (g) + CH3OH (l) ----> CH3COOH (l) at 298K, from the standard entropies and enthalpies of formation given in the data sheet.

Answer 1

The reaction can be split into the following steps:

1. CO (g) + 1/2 O2 (g) ---> CO2 (g) ΔG° = -137.3 kJ/mol
2. H2 (g) + 1/2 O2 (g) ---> H2O (l) ΔG° = -237.2 kJ/mol
3. CH3OH (l) ---> CH4 (g) + H2O (l) ΔG° = 168.6 kJ/mol
4. CH4 (g) + CO2 (g) ---> CO (G) + 2 H2O (l) ΔG° = 49.4 kJ/mol

Overall reaction:

CO (g) + CH3OH (l) ---> CH3COOH (l)

ΔG° = [(1 * ΔGf°(CH3COOH) + 1 * ΔGf°(H2O) + 1 * ΔGf°(CO) + 1 * ΔGf°(CH4)) - (1 * ΔGf°(CH3OH) + 1 * ΔGf°(CO))]
ΔG° = [( -388.51 + -237.13 + -137.26 + -74.87 ) - ( -166.17 + -110.53 )]
ΔG° = [-837.77 - (-276.7)]
ΔG° = -561.07 kJ/mol

Therefore, the standard Gibbs energy change for the reaction CO (g) + CH3OH (l) ---> CH3COOH (l) at 298K is -561.07 kJ/mol.