Reactive gas solubility in water: An empirical relation

An empirical equation is proposed to describe the solubility vs pressure relation for some reactive gases. The systems under consideration are ammonia/water, sulfur dioxide/water, chlorine/water, and hydrogen chloride/water. It is assumed that the reactive gases are dissolved in water by two mechanisms: one described by Henry's law and the other by a Langmuir type equation. Out of the four systems only hydrogen chloride showed no Henry's type of sorption, and a threshold concentration term was added to validate the model. The proposed equation fits well to the solubility/pressure data from the literature. A possible variation in the:values of the empirical coefficients with the change in the water chemistry (pH, ionic strength) is also discussed.