Computation of physicochemical parameters, namely pH, in complex (bio)chemical systems: extension to gas-liquid systems.

The first model has been proposed to compute, in complex liquid (bio)chemical systems, a number of physicochemical parameters, namely pH, concentration of one of any chemical species, partition between acid-base forms, global charge, or ionic strength, assuming the physicochemical equilibrium state. The extension of the present model, described here, permits moreover the computation of gas-liquid distributions, specific gas volumes, or total pressures. The model solely requires the knowledge of existing thermodynamic constants and of the concentration of every chemical species other than the species under examination. The model elicits a unique equilibrium state. Computed values agreed with experimental measurements, thereby validating the model. Digital computer programs were prepared to use the proposed algorithms.