Hydrogen chloride, aqueous, partial pressures

Here is an example. Pure HCl (hydrogen chloride) is a gas that is very soluble in water. A plot of the partial pressure of gaseous HCl in equilibrium with aqueous HCl, as a function of the solution molality (Fig. 10.1), shows that the limiting slope at infinite dilution is not finite, but zero. What is the reason for this non-Henry s law behavior It must be because HCl is an electrolyte—it dissociates (ionizes) in the aqueous environment. 

Thus, the chemical cell, consisting of an aqueous solution of hydrogen chloride (activity a, concentration c), a platinum-hydrogen electrode (partial pressure of hydrogen p), and a silver-silver chloride electrode, both with copper terminals, is represented by the diagram... 

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