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.