AbstractThe influence of supporting electrolytes on the equilibrium Cr2O72−+ H2O ⇄ 2 HCrO4− has been investigated with a view to comparing this influence with that exerted on the rates of reactions of similar charge‐types. Neither the influence on the equilibrium constant nor that on the rate constant of the back reaction was found to be uniquely determined by the principle of ionic strength. These results, together with examples from the literature, show that there seems to be nothing special about environmental influence on the kinetics of reactions. It is suggested that what makes prediction difficult is the fact that in both cases activity coefficients appear in a combination which is different from that encountered in the mean activity coefficient.A spectrophotometric method is employed. The value of the equilibrium constant at zero ionic strength has been found equal to 4.4 × 10−2; the heat of reaction is 3.8 Kcal mol−1. The discrepancies between these values and those reported in the literature a