. 2005 Dec;71(12):7838–7845. doi: 10.1128/AEM.71.12.7838-7845.2005

TABLE 1.

Standard Gibbs free energy changes (ΔG°′) for anaerobic reactions (pH 7)^a

Compound	Reaction	ΔG°′ (kJ mol⁻¹)
Hydrogen-releasing reactions
Propionate	CH₃CH₂COO⁻ + 3H₂O → CH₃COO⁻ + HCO₃⁻ + 3H₂ + H⁺	76.1
Ethanol	CH₃CH₂OH + H₂O → CH₃COO⁻ + 2H₂ + H⁺	9.6
1-Propanol	CH₃CH₂CH₂OH + H₂O → CH₃CH₂COO⁻ + 2H₂ + H⁺	3.0
Hydrogen-consuming reaction
Hydrogen	H₂ + 1/4HCO₃⁻ + 1/4H⁺ → 1/4CH₄ + 3/4H₂O	−33.9
Syntrophic methanogenesis
Propionate	CH₃CH₂COO⁻ + 3/4H₂O → 3/4CH₄ + CH₃COO⁻ + 1/4HCO₃⁻ + 1/4H⁺	−25.6
Ethanol	CH₃CH₂OH + 1/2HCO₃⁻ → 1/2CH₄ + CH₃COO⁻ + 1/2H₂O + 1/2H⁺	−58.2
1-Propanol	CH₃CH₂CH₂OH + 1/2HCO₃⁻ → 1/2CH₄ + CH₃CH₂COO⁻ + 1/2H₂O + 1/2H⁺	−64.8

ΔG°′ values were obtained from references 27 and 36.