Anomalous energy yields in thermodynamic calculations: importance of accounting for pH-dependent organic acid speciation (original) (raw)

This paper investigates the significance of accounting for pH-dependent organic acid speciation in thermodynamic calculations related to methanogenic ecosystems. It emphasizes that neglecting the speciation of weak acids can introduce errors in Gibbs free energy (ΔG) calculations, particularly at pH values near the acid's pK_a. The authors demonstrate that while these errors may be minor, they are crucial given the low energy margins in anaerobic ecosystems where methanogenesis occurs. Through illustrative figures, they reveal how pH variations affect the energetics of methane production, ultimately advocating for more precise methodologies in energy yield calculations.