Kinetic Salt Effect in the 18O-Exchange Reaction between Bromate and Water

The kinetic salt effect in the ¹⁸O-exchange reaction between bromate ion and water has been investigated at 60° in a range of ionic strength from 0.02M < I < 1.9M using NaNO₃ or NaClO₄ as inert salts. From the experimental data the following relation was deduced for the uncatalysed reaction path In the H⁺-catalysed reaction path the Brønsted-Davies equation was obeyed up to I ? 0.1M At I > 0.8M the sign of Δ logk₂/Δ I^1/2 was positive. The theoretical interpretation of these results is consistent with the mechanistic evidence obtained previously from the rate law and the solvent isotope effects.