Journal of the Serbian Chemical Society 2008 Volume 73, Issue 11, Pages: 1113-1122
https://doi.org/10.2298/JSC0811113O
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Conductometric and pH metric investigations of the oxalic acid and NaAsO2 reaction
Obradović Mirjana V. (Odsek za hemiju, Prirodno-matematički fakultet, Niš)
Sunarić Slavica M. (Odsek za farmaciju, Medicinski fakultet, Niš)
Mitić Snežana S. (Odsek za hemiju, Prirodno-matematički fakultet, Niš)
Veselinović Dragan S. (Fakultet za fizičku hemiju, Beograd)
The reaction between NaAsO2 and oxalic acid was studied by pH-metric and conductometric measurements, applying the methods of continual variation and pH-metric and conductometric titration. It was found that oxalic acid forms a complex anion of the type [AsOC2O4]-. The relative stability constant of the complex at ionic strengths, I, of 0.10 (log Kr = 4.70), 0.20 (log Kr=4.51), 0.50 (log Kr = 4.24) and 0 (log K 0 = 5.05) and thermodynamic parameters were calculated using the data obtained by pH-metric measurements at 25.0±0.1°C (DH = 10.5 kJ mol-1, DG = -29.0 kJ mol-1, DS = 133 J mol-1 K-1).
Keywords: arsenic(III), oxalic acid, complex, conductometry, pH-metry