Electromigration of carrier-free radionuclides : III. Oxalate and tartrate complexes of ytterbium(III_ in aqueous solution

Abstract

The dependences of the overall ionic mobilities, u , of Yb(III) on the oxalate (C 2O 2− 4) and tartrate (C 4H 4O 2− 6) concentrations in aqueous nitrate electrolytes of overall ionic strength 0.01 and temperature 298.1(1)K were obtained by direct measurements of the electromigration mobilities of carrier-free 169Yb-Yb(III). Mathematical processing of the experimental data allowed the individual concentration constants of Yb(III) to be determined: [Yb(C 2O 4)] +, log K 1 = 5.80(5); [Yb(C 2O 4) 2] −, log K 2 = 4.06(3); [Yb(C 4H 4O 6)] +, log K 1 = 4.61(6). The individual ionic mobilities, u 0 i , of the ions were u 0 Yb 3+ = +6.01(5) · 10 −4 cm 2 s −1 V −1, u 0 [Yb(C 2O 4)] + = + 2.5(2) · 10 −4 cm 2 s −1 V −1, u 0 [Yb(C 2O 4) 2] − = − 2.5(1) · 10 −4 cm 2 s −1 V −1, u 0 [Yb(C 4H 4O 6)] + = + 2.3(5) · 10 −4 cm 2 s −1 V −1. It is shown that Yb(III) is not hydrolysed in neutral (pH < 8) solutions.