Constantes de acidez de ácidos dipróticos a partir de titulações potenciométricas: ilustração dos princípios do cálculo através da construção de um algoritmo muito simples

• Autor(a) principal: Gonçalves,Elsa M.
• Data de Publicação: 2011
• Outros Autores: Conceição,António C. L.
• Tipo de documento: Artigo
• Idioma: por
• Título da fonte: Química Nova (Online)
• Texto Completo: http://old.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40422011000600027
• topic: dissociation constants; potentiometric titrations; algorithm

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.