Acidity constants of diprotic acids from potentiometric titrations: principles of the calculation illustrated through the construction of a simple algorithm

Quimica nova

Conceição, António C. L.¹  Gonçalves, Elsa M.² 

[1] Departamento de Química e Bioquímica, Lavradio, Portugal;Universidade de Lisboa, Lisboa

关键词: dissociation constants;    potentiometric titrations;    algorithm.;   

DOI  :  10.1590/S0100-40422011000600027

学科分类：化学（综合）

来源: Sociedade Brasileira de Quimica

【 摘 要 】

This work describesthe creation of an very simple calculation algorithm, based in basic chemicaland mathematic principles, for the calculation of weak diprotic acid dissociationconstants as, for example, amino acids, from potentiometric titrations. Foran easier understanding of the algorithm the logical reasoning of this calculusis schematized in a diagram of blocks. In the second part of the work the algorithmis applied to an Excel calculation sheet to determine the dissociation constantsof Nicotinic Acid and Glycine, from the respective potentiometric titrationcurves. The values obtained using this algorithm are compared with those estimatedby Hyperquad2008 (program generally used for this type of calculus) andalso with the values of a stability constants database.

【 授权许可】

CC BY