Determination of carbonate alkalinity and apparent dissociation constants in a multiprotolytic system

Abstract

A method for analysing the carbonate system in a multicomponent solultion is presented, which does not need knowledge of the total composition of the system. It is based on two titrations with acid, starting at the same pH, one of the original solution and the other after removal of carbonate species as carbon dioxide and restoration of the pH to the value for the original solution by addition of carbonate-free base. The differential titration curve, obtained by subtracting one titration curve from the other, is associated with the carbonate system. A procedure is proposed for calculating from the differential titration curve the apparent first and second dissociation constants of carbonic acid, total CO 2 and the carbonate alkalinity at the original pH of the solution.