Charge Balance II

The point here is that the charge-balance option is a replacement for the choice of a basis species concentration. Thus, in our discussion of the Phase Rule, each time we mentioned b basis species, we could have said b—1 basis species plus the charge-balance condition on an additional basis species. 

however, that it is not a good idea to balance on H+ in order to calculate the pH, unless it is a hypothetical model solution with perfectly known concentrations. This is because the concentration of H+ is such a small quantity that tiny errors in the analytical concentrations of the other elements will render the calculated p meaningless. Choosing Cl- as the balancing species is usually fine, unless the solution has a 

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