Simultaneous Determination of Equivalence Volumes and Equilibrium Constants from Potentiometric Titrations

Abstract

Linear equation, concerning equivalence volume, concentration of ion and volume of titrant, was proposed for the simultaneous determination of equivalence volumes and equilibrium constants in potentiometric titrations.
This equation i s applicable to monobasic acid-base, chelometric, precipitation, and redox titrations without approximations: y-=v_a+P⋅x where v_a is equivalence volume, x and y are functions of concentration of ion, determined by an ion-selective electrode, and volume of the titrant, respectively; in the case of redox titration, x is a function of ion concentration. P is a constant relating to equlibrium constant. Equivalence volume and equilibrium constant are determined in terms of the linear extrapola tion and the slope of y vs. x plot.
This method can be applied satisfactorily to the potentiometric titration whose experimental curve does not show a sharp inflection point or a symmetrical shape.