Hydrogen ion concentration versus pH.

There appears to be a tendency to convert pH values into "hydrogen ion concentrations" using the antilog of negative pH values. The present communication describes the thermodynamic basis of pH to explain that the above procedure is erroneous and that pH values should be treated as primary variables. Acidity expressed by the hydrogen ion concentrations measured by titrations (base excess or base deficit) has no bearing with the "hydrogen ion concentrations" derived by the antilog of negative pH.