Microcalorimetric investigation on the kinetics of the oxidation of ascorbic acid with hydrogen peroxide

Based on the thermokinetic theory, a novel thermokinetic research method‐self‐function regression method, which could be used to determine the kinetic parameters kl. k 2 and k‐ 1 of the complex reaction: B + \documentclass{article}\usepackage{chemarr}\pagestyle{empty}\begin{document}${\rm C} \xrightleftharpoons[{k_{- 1}}]{{{\rm k}_{\rm 1}}} {\rm I} \xrightarrow[]{{\rm k}_{\rm 2}} {\rm P},$\end{document} , was proposed in this paper. The kinetics of the reaction of ascorbic acid (H 2 A) with hydrogen peroxide was investigated at pH=5‐7 and T=298.15 K, and the kinetic parameters k 1 k 2 and k ‐1 were obtained with this method. The kinetics of the reaction was investigated in detail. The kinetic parameters of the oxidation of ascorbic monoanion (HA − ) and ascorbic dianion (A 2 ‐) with hydrogen peroxide were 3.33×10 −3 s −1 and 25.48 s −1 at 298.15 K, respectively. The molar enthalpy change for the reaction was ‐554.64 kJ · mol −1 in phosphate buffer solution at pH 7 and at 298. 15 K.