Estudo potenciométrico dos equilíbrios no sistema manganês (II) / azoteto / The potentiometric study of complex formation in the manganese (II)/azide system

AUTOR(ES)

Horacio Dorigan Moya

DATA DE PUBLICAÇÃO

1993

RESUMO

The equilibria of complex formation between manganese(II) cations and azide anions were studied in aqueous medium by an indirect potentiometric method, at 25°C and ionic strengh 2.0 M (NaClO4). The equilibrium data were based on pH measurements of Mn(II) in N3¯/HN3 buffers. Metal ion concentration changing from 20 to 100 mM have defined one single formation curve of n_ (Bjerrum function) vs. [N 3 ¯ ] which is an evidence that only mononuclear species ara present in the working solutions. Integration of the formation curve from the best n¯vs. [N3¯] data leads to Fronaeus function data. They were properly treated to obtain the formation by a variety of methods (graphic and mathematical). The best set formed is: β1 = 4,15 ± 0,02 M-1 , β2 = 6,61 ± 0,04 M-2 , β3 = 3,33 ± 0,02 M-3 , β4 = 0,63 ± 0,01 M-4 . The complex are weaks and are is agreement with the Irving and Williams rule, i. e., less stable than the corresponding complexes of Ni(II) and Co(II). At ligand concentration higher t than 1,0 M there were conditions for a slow spontaneous oxidation of manganese(II) complexes to manganese to manganese(III), with remarkable spectral changes.

ASSUNTO(S)

azide azoteto constantes de equilibrio manganês manganese métodos eletroquímicos potenciometria potentiometry stability constants

Documentos Relacionados

• Estudo potenciométrico sobre a formação de complexos no sistema ferro (III)/azoteto, em meio não totalmente aquoso
• Estudo crítico de equilíbrios no sistema cobalto (II)/tiocianato
• ESTUDO TEÓRICO DA INTERAÇÃO DO OXIGÊNIO MOLECULAR COM OS COMPLEXOS DE DIBENZOTETRAAZA[14]ALUNENO DE FERRO (II) E MANGANÊS (II)
• Aproveitamento analítico da reação cobre(II)-azoteto, equilíbrios e dados termodinâmicos
• A existência de onda catalítica no sistema cobalto (II) azeteto/ácido azotídrico