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

Química Nova

Departamento de Química e Bioquímica, Lavradio, Portugal¹  Conceição, António C. L.¹  Gonçalves, Elsa M.¹  Universidade de Lisboa, Lisboa¹  Centro de Química Estrutural, Lisboa, Portugal¹ 

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 describes the creation of an very simple calculation algorithm, based in basic chemical and mathematic principles, for the calculation of weak diprotic acid dissociation constants as, for example, amino acids, from potentiometric titrations. For an easier understanding of the algorithm the logical reasoning of this calculus is schematized in a diagram of blocks. In the second part of the work the algorithm is applied to an Excel calculation sheet to determine the dissociation constants of Nicotinic Acid and Glycine, from the respective potentiometric titration curves. The values obtained using this algorithm are compared with those estimated by Hyperquad2008 (program generally used for this type of calculus) and also with the values of a stability constants database.

【 授权许可】

Unknown