Stability Constants and Related Thermodynamic Functions of Some Rare-Earth Metal Complexes of Sodium 2-[4-Amino-3-(1,2,4-Triazolylazo)]Naphthol-4-Sulphonate

Department of Chemistry, University of Delhi, Delhi-110 007 Manuscript received 23 July 1981, revised 17 December 1981, accepted 23 May 1982 The stability constants of La2+, Pr2+, Nd2+, SM2+, Gd2+,Tb2+, Dy2+, Yb2+ and Y2+ complexes of sodium 2-[4-amino-3-(1,2,4-triazolylazo))naphthol-4-sulphonate have been determined in aqueous medium at different ionic strengths and temperatures employing the Bjerrum-Calvin titration technique as modified by Irving and Rossetti. The free energy, enthalpy and entropy changes involved in complexation have been determined