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Aplicação de um corante tiazolilazo como indicador ácido-base e determinação das suas constantes de ionização ácida

2009; Brazilian Chemical Society; Volume: 32; Issue: 7 Linguagem: Inglês

10.1590/s0100-40422009000700042

ISSN

1678-7064

Autores

Regina Terumi Yamaki, Daniel Rodrigues Vieira, Cléber Galvão Novaes, Hygor Rodrigues De Oliveira, Valfredo Azevedo Lemos, Sandra Helena Vieira de Carvalho,

Tópico(s)

Chemistry and Chemical Engineering

Resumo

ITS ACID IONIZATION CONSTANTS.The pKa values of the 6-[2´-(6´-methyl-benzothiazolylazo)]-1,2-dihydroxy-3,5-benzenedisulfonic acid (Me-BDBD) have been determined at 25 °C, in 0.10 mol L -1 NaCl medium by spectrophotometric method.The SQUAD computer program was used to process experimental data in pH range 1.78 -11.54 and 290 -720 nm.The pKa values obtained were 4.60 ± 0.04 and 9.48 ± 0.02.The Me-BDBD reagent was applied as indicator in titration of acid-base.The results were compared with phenolphthalein and bromocresol green indicators.Statistical t and F tests indicated that there were no statistically significant differences between the results for indicators with good agreement.

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