Observations related to the oxidation of iodide to iodine (I2) or hypoiodic acid (HIO) by MnO2 were continued. The formation of triiodide presumable involves the adsorption of iodide onto the MnO2 surface (perhaps displacing a surface hydroxyl group). The iodide should be subsequently oxidized and released back into solution as IOH or I2, which rapidly forms I3 -. The kinetic data has been modeled as a first order process. First order rate constants have been obtained for the formation of iodine in the presence of MnO2. The increase in iodide oxidation rates with MnO2 concentration is evident in the data. The reaction rate increases with iodide concentration although the dependence is not first order (an order of 1.4 appear to fit the data). The oxidation rate also increases with temperature and has a apparent activation energy of 16.2 kJ/mol
