Formulation of the System of Isohydric Solutions

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4

titrant in such systems can be reversed. The formulae for

more complicated systems are given in [4]. The iso-

hydricity property can be formulated for the systems

where only acid-base equilibria occur Equation (14),

relates analytical concentrations of strong acid HB and

weak acid HL. Such an interesting property is not di-

rectly relevant to buffering action. Nevertheless, it is

on-line with a general property desired from buffering

systems.

The systems of isohydric solutions have a unique fea-

ture, not stated in other acid-base systems. It is the con-

stancy of ionic strength (I), not caused by presence of a

basal electrolyte. The conjunction of properties: pH =

const, I = const, together with constancy of temperature

(T = const) provided a useful tool for a sensitive method

of determination of pK1 values for weak acids, as indi-

cated and applied in [4,5]. This method is illustrated with

some examples taken from [4].

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