Collect. Czech. Chem. Commun. 2010, 75, 653-663
Published online 2010-06-17 08:30:53

Reduction of indium(III) at dropping mercury electrode in the presence of pyridine in aqueous and ethanol–water media

Vinita Sharmaa,* and Krishna D. Guptab

a Department of Chemistry, Swami Keshvanand Institute of Technology, Management & Gramothan, Jaipur-302025, India
b Department of Chemistry, Malaviya National Institute of Technology, Jaipur-302017, India


The reduction of indium(III) at dropping mercury electrode in aqueous as well as in 25% ethanol–water media in the presence of pyridine has been studied at a constant ionic strength (0.1 M KNO3) and at 30 and 40 °C. The reduction is diffusion-controlled but the electrode process is quasi-reversible in both media. The reversible half-wave potential values, E1/2r, have been obtained by Gelling’s method. The plot of E1/2r versus pyridine concentration is a straight line and the number of ligands, j, was determined from the slope. This shows the formation of a single complex. The stability constant has been determined by Lingane’s method. In(III) forms one complex species with composition 1:1, [In(py)]3+. The values of thermodynamic parameters ΔG, ΔH and ΔS of the complexation reaction have also been determined at 30 °C.

Keywords: Electroreduction; Indium; Pyridine; Polarography; Stability constants; Thermodynamics.

References: 72 live references.