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Chromium(III)-catalysed cerium(IV) oxidation of arsenic(III) in aqueous sulphuric acid

1987; Royal Society of Chemistry; Issue: 3 Linguagem: Inglês

10.1039/dt9870000573

2050-5671

Shivamurti A. Chimatadar, Sharanappa T. Nandibewoor, M I Sambrani, Javali R. Raju,

Inorganic and Organometallic Chemistry

The chromium(III)-catalysed cerium(IV) oxidation of arsenic(III) studied in aqueous sulphuric acid follows the rate law (i) where the right-hand side represents the catalysed path. In equation (i), the –d[CeIV]//dt–ku[AsIII][CeIV]=2kakcβ4KIP[CeIV][CrIII][AsIII][SO42–]3[HSO4–]2[H+]2//(1 +β1[SO42–]+β2[SO42–]2+β3[SO42)]2[HSO4–]+β4[SO42–]2[(HSO4–]2[H+])(1 +KIP[SO42–])×{kbK5[CeIII][SO42–]3//(1 +K5[SO42–]3)+kc[AsIII][H+]}–1(i)β's are the stability constants of the different cerium(IV) sulphate complexes and KIP and K5 are the equilibrium constants of the species Cr3+SO42– and Ce(SO4)33– respectively. A chromium(IV) species is involved in the catalysed path. Increasing sulphuric acid concentrations effect rate increases of both the uncatalysed and catalysed paths and the active oxidant is understood to be the species H3Ce(SO4)4–.