Thermodynamics of complexing between (+)-tartaric acid and lanthanum(III) ion in aqueous solution

Abstract

The stability constants of the lanthanum-tartrate complexes LaTar⁺, LaTar₂^–, and LaHTar²⁺ have been determined in 0·1, 0·2, and 0·4M(Me₄N)Cl media †; by potentiometric titration by use of a glass electrode. Thermodynamic constants have been determined at 15, 25, and 35 °C by the same method and standard enthalpy and entropy changes obtained from the temperature variation of the constants. Some structural implications of the results are discussed.