Kinetics of Complexation of Silver(I) with Thiosulfate Ion in Aqueous Solution.

摘要

A specific rate constant for the rapid complexation of Ag(+) ion by thiosulfate ion in aqueous solution was determined using the recently developed laser optical-acoustic technique for sound absorption measurements. In aqueous solution the predominant complexed species is the 1:2 ion Ag(S2O3)2(3-). Over the 15-230 MHz frequency range of the measurements two relaxations were observed. Both relaxations have been attributed to the stepwise mutual approach of AgS2O3(-) and S2O3(2-), with the elimination of coordinated water to form the 1:2 complex ion, i.e. to the second association step in the complete reaction. At 25 deg the specific rate constant k3 for this association reaction is 3.5 x 10 to the 9th power/M/sec. The result is compared with the theoretical value assuming diffusion control, with the theoretical value for the preceding step, and with a previously published value for Ag(+) complexation by o-phenanthroline. (Author)