In an aqueous solution the velocity constants for very rapid reversible reactions of the type MeXi-1 X MeXi- are determined from the line width of the magnetic nuclear resonances of 81Br, 79Br and 127I. The tested substances are as follows CdBr2, HgBr2, ZnBr2, CdI2 and ZnI2, which, when in solution, form ions or neutral molecules of the type Me, MeX, MeX2, MeX3- and MeX4-2. The cited results of measurements show that by adding small amounts of the substance to a fully dissociated electrolyte KBr,KI the nuclear resonant lines of Br and I will broaden considerably. The equation for calculating the rate constant can be deduced from the measured broadening of the line. This is followed by a numerical evaluation of the rate constant for each of the five examined cases and by a discussion of the necessary equilibrium constants and activity coefficient. In addition, some numerical values, from measurements are given for the transverse relaxation time T2 of 881Br and 79Br for the various ions.
Trans. from Zeitschrift fuer Elektrochemie (West Germany) v65 1961, by G. Duffy.