Balance of charges in a chemical reaction

In electroneutral systems, electric charges can be transferred from one ion to another, as for example in the chemical reaction 

It is often convenient to discuss chemical reactions in terms of the two or more electrochemical reactions into which they can be divided. For example the chemical reaction (27.11) can be regarded as the sum of the two electrochemical reactions 

Mean Chemical Potentials and Mean Ionic Activity Coefficients. 

For a weak electrolyte such as acetic acid the condition of equilibrium for the ionization reaction is 

We have seen in 2 that if we consider only electroneutral systems, the chemical potentials of the two ions cannot be measured separately. For this reason it is convenient to define the mmn chemical potential of the two ions by the relation 

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In this way a whole set of values can be built up. Such values are often known as conventional standard enthalpies of formation, the word "conventional referring to the arbitrary value of zero for the proton. In spite of the arbitrariness of the procedure, one always obtains correct values when one uses these conventional values in making calculations for reactions this follows from the fact that there is always a balancing of charges in a chemical reaction. 

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