Thermodynamic Constants of Gallium (III) Chelates of Some Halo Derivatives of 8-Hydroxyquinoline-5-Sulphonic Acid
| Main Authors: | BALRAJ K. AVINASHI, SAMIR K. BANERJI |
|---|---|
| Format: | Article Journal |
| Bahasa: | eng |
| Terbitan: |
, 1972
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| Subjects: | |
| Online Access: |
https://zenodo.org/record/6446895 |
Daftar Isi:
- Chemical Laboratories, Birla Institute of Technology & Science, Pilani (Rajasthan) Received 7 July 1971, revised MSS received 3 April 1972 Gallium(III) forms in aqueous medium, 1 : 3 chelates with 7-chloro-8-hydroxyquinoline- 5-sulphonic acid (R1) and 7-bromo-8-hydroxyquinoline-5-sulphonic acid (R2), both having \(\lambda\)max at 355 nm, stable in the \({p}\)H ranges 3.3-7.6 and 2.9—5.9 respectively. The stability constants calculated by the mole-ratio method and the method using molecular extinction coefficient data have been found to be log K ═ 13.5±0.2 and 13.6±0.2 respectively for Ga(R1)3 and Ga(R2)3 chelates at 20°. The values of free energy of formation in these chelates come out to be Δ F = -18.1±0.3 kcal/mole and —18.3±0.3 kcal/mole at 20°. The enthalpy changes and entropy changes calculated by the temperature coefficient method and Gibbs-Helmholtz equation respectively are found to be 1.44 kcal/mole and 65.4 e.u. for the Ga(R1)3 chelate and 7.78 kcal/mole and 87.8 e.u. for the Ga(R2)3 chelate.