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

Abstract

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).