Acta Phys. -Chim. Sin. ›› 2001, Vol. 17 ›› Issue (12): 1067-1071.doi: 10.3866/PKU.WHXB20011203

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Studies of Mn(III)/Mn(II) on Platinum Electrode in Acetic Acid-Anhydride Solution

Pan Zhan-Chang;Chen Qi-Yuan;Huang Hui-Min   

  1. College of Chemistry and Chemical Engineering, Central South University, Changsha 410083;Faculty of Chemical Engineering and Light Industry, Guangdong University of Technology, Guangzhou 510090
  • Received:2001-04-04 Revised:2001-07-26 Published:2001-12-15
  • Contact: Pan Zhan-Chang

Abstract: The electrochemical behavior of Mn(III)/Mn(II) on platinum electrode in acetic acid-anhydride was investigated. The results show that the conditional electrode potential of Mn(III)/Mn(II) was 0.719 V(vs SCE) in the solution of 1.5 mol•L-1 KOAc+HOAc-Ac2O(3:1 volume ratio) at 25 ℃. The results of potential sweep and RDE on platinum electrode show that the rate determing step of the electrode processes for Mn(II) anodic oxidation was a charge-transfer step. The anodic charge-transfer kinetic parameters were determined. The results show that the anodic charge-transfer coefficient is 0.347, the exchange current density i0 is 5.84×10-6 A•cm-2, the conditional charge-transfer rate constant ka is 1.35×10-8 m•s-1 at 25 ℃. The rate was found to be first order with respect to the concentration of both Mn(II) and OAc-.

Key words: Mn(III)/Mn(II), Acetic acid, Conditional electrode potential, Anodic oxidation, Change-transfer kinetic parameters