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Kinetics of cerium (IV) oxidation of mandelic acid. Ionic strength and specific cation effects
Author(s) -
Arcoleo Gioacchina,
Calvaruso Giuseppe,
Cavasino F. Paolo,
Dio Emanuele Di
Publication year - 1979
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550110407
Subject(s) - chemistry , ionic strength , inorganic chemistry , cerium , mandelic acid , reaction rate constant , redox , sulfuric acid , lithium (medication) , electrolyte , kinetics , ionic radius , aqueous solution , ion , organic chemistry , electrode , medicine , physics , quantum mechanics , endocrinology
The kinetics of the redox reaction between mandelic acid (MA) and ceric sulfate have been studied in aqueous sulfuric acid solutions and in H 2 SO 4 MClO 4 (M + = H + , Li + , Na + ) and H 2 SO 4 MHSO 4 (M + = Li + , Na + , K + ) mixtures under various experimental conditions of total electrolyte concentration (that is, ionic strength) and temperature. The oxidation reaction has been found to occur via two paths according to the following rate law: rate = k [MA] [Ce(IV)], where k = k 1 + k 2 /(1 + a) 2 [HSO 4 − ] 2 = k 1 + k 2 /(1 + 1/a) 2 [SO 4 2− ] 2 , a being a constant. The cations considered exhibit negative specific effects upon the overall oxidation rate following the order H + ⩽ Li + < Na + < K + . The observed negative cation effects on the rate constant k 1 are in the order Na + < Li + < H + , whereas the order is in reverse for k 2 , namely, H + ⩽ Li + < Na + . Lithium and hydrogen ions exhibit similar medium effects only when relatively small amounts of electrolytes are replaced. The type of the cation used does not affect significantly the activation parameters.