Acid dissociation constant of the carboxyl radical. Pulse radiolysis studies of aqueous solutions of formic acid and sodium formate

Abstract

Pulse radiolysis of aqueous solutions of formic acid and formate ion in the pH range 0–13 shows (i) that the absorption spectrum of the carboxyl radical is constant between pH 2.5 and 13, but decreases in intensity between pH 2.5 and 0; (ii) that the effect of ionic strength on the rate of reaction of the radical with itself is the same at pH 2.7 and 7 and is consistent with the radical having unit negative charge at pH 2.7. The data presented indicate that the pK of the radical is 1.4.