Potentiometric Investigation of the Weak Association of Sodium and Oxalate Ions in Aqueous Solutions at 25°C

Andrew Tromans; Glenn Hefter; Peter M. May

doi:10.1071/CH04230

RESEARCH ARTICLE

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Potentiometric Investigation of the Weak Association of Sodium and Oxalate Ions in Aqueous Solutions at 25°C

Andrew Tromans ^A , Glenn Hefter ^A ^B and Peter M. May ^A

+ Author Affiliations

- Author Affiliations

^A Chemistry Department, Murdoch University, Perth WA 6150, Australia.

^B Corresponding author. Email: g.hefter@murdoch.edu.au

Australian Journal of Chemistry 58(3) 213-217 https://doi.org/10.1071/CH04230
Submitted: 1 October 2004 Accepted: 19 January 2005 Published: 15 March 2005

Abstract

The formation constant β(NaOx⁻) of the extremely weak ion pair formed between sodium (Na⁺) and oxalate (Ox²⁻) ions in aqueous solutions has been determined at 25°C as a function of ionic strength in tetramethylammonium chloride by Na⁺ ion-selective electrode potentiometry. The effects of trace Na⁺ impurities from all reagents were accounted for. An extrapolated value for β ^o of 6.6 ± 0.5 M⁻¹ was obtained at infinite dilution, which is in good agreement with literature values. Attempts to measure this constant in 1 M CsCl media gave a β(NaOx⁻) value of 0.00 ± 0.06 M⁻¹, probably because of competition between Cs⁺ and Na⁺ for Ox²⁻.

Acknowledgments

The authors acknowledge the support of the A.J. Parker Cooperative Research Centre for Hydrometallurgy in the form of a postgraduate scholarship for A.T.

References

Potentiometric Investigation of the Weak Association of Sodium and Oxalate Ions in Aqueous Solutions at 25°C

Abstract

Acknowledgments

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