ON THE USE OF DIMENSIONLESS PARAMETERS IN ACID-BASE THEORY .6. THE BUFFER CAPACITIES OF EQUIMOLAR BINARY-MIXTURES OF MONOVALENT WEAK PROTOLYTES AS COMPARED TO THAT OF BIVALENT PROTOLYTES

The general equation for the relative molar buffer capacity, earlier shown to be valid for bivalent acids, bases, and ampholytes, is shown to hold also for equimolar binary mixtures of monovalent protolytes if only the parameter s = root K-1'/4K(2)' is exchanged for r = s + 1/4s. The same apples to the equations for the mean valence of the two classes of protolytes. As a consequence thereof, the titration and buffer capacity curves of a bivalent protolyte are identical with those of a monovalent protolyte with a pK' value equal to root K-1'K-2' of the bivalent one (the isoprotic point of an ampholyte). For a hypothetical bivalent acid, base, or ampholyte with s = 1, Delta pK' = log 4, this implies that the intrinsic rather than the hybrid dissociation constants are responsible for the titration and buffer capacity curves.