An arbitrary correction function for CO(2) evolution in acid-base titrations and its use in multiparametric refinement of data.
A great number of acid-base titrations are performed under an inert gas flow: in the procedure, a variable amount of CO(2)-from carbonated reactants-is carried away and thus prevents strict application of mass-balance equations. A function for the CO(2) evolution is proposed and introduced into the general expression for the volume of titrant. Use of this expression in multiparametric refinement yields, besides the usual values (concentrations, acidity constants...), a parameter characteristic of this departure of CO(2). Furthermore, a modified weighting factor is introduced to take into account the departure from equilibrium caused by the slow CO(2) evolution. The validity of these functions was successfully tested on three typical examples: neutralization of strong acid by sodium carbonate, of sodium carbonate by strong acid, and of a mixture of hydrochloric acid, 4-nitrophenol and phenol by carbonated potassium hydroxide.
Wozniak
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Ecole Nationale Supérieure de Chimie de Lille, Université de Lille I, BP 40, 59650 Villeneuve d'Ascq, France.
Nowogrocki
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