The pKa of acid-base indicators and the influence of colloidal systems.

被引：32

作者：

Fernandes Previdello, Bruno Alarcon ^{[1
]}

Rodrigues de Carvalho, Fernando ^{[1
]}

Tessaro, Andre Luiz ^{[1
]}

Roberto de Souza, Vaguer ^{[1
]}

Hioka, Noboru ^{[1
]}

机构：

[1] Univ Estadual Maringa, Dept Quim, BR-87020900 Maringa, Parana, Brazil

来源：

QUIMICA NOVA | 2006年 / 29卷 / 03期

关键词：

pK(a); acid-base indicator; colloidal systems;

D O I：

10.1590/S0100-40422006000300032

中图分类号：

O6 [化学];

学科分类号：

0703 ;

摘要：

An experiment is proposed that can be included in undergraduate courses of chemistry. The subject is the acidity of organic compounds, which are employed as pH indicators, particularly in acid-base titrations. The indicators used are methyl orange, bromophenol blue and bromocresol green in aqueous medium. The influence of colloidal systems on the equilibrium is evaluated by the pK(a). The colloids employed are surfactants like sodium dodecyl sulfate, cetyl-trimethylammonium bromide and a polymeric non-ionic F127 (pluronics). The effect of stabilization promoted by the system on the acidic or basic structure of the indicator establishes the action mechanism of the colloid on the pK(a) values.

引用

页码：600 / 606

页数：7

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