Solvent Effect on the Kinetics of Reaction between Methyl Orange and Peroxydisulphate Ion in Presence of Bromide Ion - Separation into Transition State and Reactant Components

School of Chemistry, Andhra University, Visakhapatnam-530 003

Manuscript received 14 February 1987, revised 26 February 1988, accepted 11 March 1988

Nuclear bromination was observed when methyl orange interacts with $S_2{O}_8^{2-}$ in presence of bromide ion. The reaction obeys zero order kinetics in the dye whereas first order kinetics in H⁺,$S_2{O}_8^{2-}$ and Br^-. Thus, the kinetics pertain to the rate· determining stage or peroxydisulphate- bromide reaction. The study in different acetic acid -water mixtures has shown that the rate increases with the Increase In acetic acid content. The separation of the solvent effect Into transition state and reactant components was accomplished from rate data and transfer free energies or $S_2{O}_8^{2-}$,Br^- and H⁺. The results indicate greater destabilisation of the reactants than transition state as acetic acid content is increased.