Kinetics of the reduction of rosaniline hydrochloride with sulphite ion in aqueous perchloric acid

Abstract

The kinetics of the reduction of rosaniline hydrochloride (RH) in perchloric acid has been investigated under pseudo-first order condition of an excess [SO₃^2-] at ionic strength of 1.0 mol dm^-3 (CH₃COONa), T = 30 0.1 o C and λ_max = 540nm. The stoichiometry of the reaction was observed to be 1:1in terms of mole ratio of RH and SO₃^2- ions consumed. The rate of reaction increased with increase in ionic strength.


The rate law is found to be of the form.


- (d/dt)[RH] = ( a + b [H⁺]^-1 ) [RH]


where a =0.30 x 10^-2 mol dm^-3 min^-1 and b= 70.58 x 10^-2 mol dm^-3 min^-1 and a pH range of 1.0 [H⁺] 3.5 x 10^-4 mol dm^-3. The results from kinetics studies and spectroscopy investigations did not implicate complex formation. A plausible mechanism is proposed for the reaction.


KEY WORDS:- Rosaniline hydrochloride, sulphite, kinetics and mechanism.


Global Journal of Pure and Applied Sciences Vol.10(4) 2004: 555-561