Conductometric and pH metric investigations of the oxalic acid and NaAsO2 reaction

• Main Authors: Obradović Mirjana V., Sunarić Slavica M., Mitić Snežana S., Veselinović Dragan S.
• Format: Article
• Language: English
• Published: Serbian Chemical Society 2008-01-01
• Series: Journal of the Serbian Chemical Society
• Subjects: arsenic(iii); oxalic acid; complex; conductometry; ph-metry
• Online Access: http://www.doiserbia.nb.rs/img/doi/0352-5139/2008/0352-51390811113O.pdf
• ISSN: 0352-5139; 1820-7421

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).