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2 Polish Journal of Chemistry

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Influence of 5-Sulphosalicyclic Acid on Redox Reaction between Fe(III) and Sn(II)

Pautieniene V., Rozovskis G., Survila A.

Polish Journal of Chemistry

2002

Vol. 76 / nr 1

103-110

Kinetics of Fe(III) reduction with Sn(II) in 0.5-2 M H2SO4 solutions involving sulphosalicylic acid (H3Ssal) has been studied. H3Ssal acts not only as an indicator for spectrophotometric determination of Fe(III) but also takes part in the redox reaction as an accelerator. The data are described by the kinetic equation obtained for the ratedetermining step of FeSsal + Sn2+_Fe2+ + Sn3+ + Ssal3- with rate constant k2 _ 1.4_10-4 M-1 s-1 at 60_C. Effect of fluoride consists in the decrease of FeSsal concentration, due to the formation of extra Fe(III)-fluoride complexes, resulting in the decrease of the reaction rate.

Tin(II) Oxidation by Oxygen and Formation of Sn(IV)–Sn(II) Colloid

Rozovskis G., Pautieniene V., Mockus Z.

Polish Journal of Chemistry

2000

Vol. 74, nr 12

1665-1674

Sn(IV) compounds, formed by a slow oxidation of Sn(II) by air in HCl or H2SO4 solutions, take part in formation of non-stable colloid particles, which coagulate rather quickly. Introduction of additional amount of Sn(IV) to the solutions of Sn(II) in HCl or H2SO4 or formation of Sn(IV) during high-rate catalytic oxidation of Sn(II) by oxygen results in formation of yellow-coloured stable colloid solutions. The colloid particles formed in HCl solution are charged positively, while formed in H2SO4 solution they are charged negatively. Sn(IV)–Sn(II) colloid particles act as an inhibitor of the process of Sn(II) oxidation by oxygen in both HCl and H2SO4 solutions. However, the colloid particles do not change the rate of Sn(II) oxidation in the H2SO4 solution with addition of Cu(II), catalyzing this reaction.