Analysis of decomposition behavior of low-concentrated ferrocyanide ion

The decomposition of low-concentrated ferrocyanide ion (less than or equal to1.28 x 10(-4) moI dm(-3)) in acidic aqueous solution was investigated. Wh ile the concentration of ferrocyanide ion (C-A) decreased with time, ferric yanide ion was formed: its concentration increased, and successively decrea sed through a maximal value. Therefore, we investigated first the decomposi tion behavior of sum of ferrocyanide and ferricyanide ions, i.e. hexacyanof errate ions. The decomposition rate of hexacyanoferrate ions which followed first-order kinetics of C-A increased with the rise in temperature and the drop in pH, That of ferrocyanide ion which also followed the first-order k inetics of C-A increased with the rise in temperature but decreased with th e drop in pH. The reaction mechanism of the decomposition of ferrocyanide i on and the formation of ferricyanide ion was discussed.