The kinetics of combination of carbon dioxide with hydroxide ions

Abstract

The velocity constant k″, of the reaction CO2 + OH - → HCO3- has been determined by the rapid thermal method over the range 0 to 40°C, by mixing together CO2 solutions with NaOH solutions of concentrations, 0.005 to 0.05 M. The effect of large variations of ionic strength has also been studied. The present thermal results are considerably more extensive than any hitherto available, but check satisfactorily with the more limited data obtained by Faurholt's carbamino method and by the manometric method. The velocity constant is related to temperature by the equation log k″ = 13.635 - (2895/T). The energy of activation is 13,250 cal. Previous manometric figures for the velocity constant ku of the reaction CO2 + H2O → H 2CO3 have been corrected with the aid of the present values of k″. The corrections were very slight at 0°C but quite appreciable at 25-38°C.