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Thermodynamics of Lanthanum Fluoride in Aqueous Sodium Perchlorate
Author(s) -
Pan Kuan,
Hsin ShuChing,
Leee MingLong
Publication year - 1974
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.197400001
Subject(s) - chemistry , sodium perchlorate , potentiometric titration , lanthanum , solubility equilibrium , perchlorate , ionic bonding , fluoride , inorganic chemistry , aqueous solution , solubility , ionic strength , sodium , electroanalytical method , ion , organic chemistry , electrochemistry , electrode
The solubility‐product constant of LaF,(s) was obtained by potentiometric titration of sodium fluoride with lanthanum perchlorate in sodium perchlorate solutions of various ionic strengths. The limiting value of pK s.p were found to be 17.65 and 17.95 at 20° and 25°C, respectively. Thermodynamic calculation from these values gives δG° =‐102.46 k J mol −1 , δH° = 100.40 k J mol −1 and δS° = 680.40 J K −1 for the reaction, La +3 (aq)+3F‐(aq)=LaF,(s), and δG° =‐1613.8k J mol ‐1, δH 1 ° =‐1594.0k J mol −1 and S ° =433.1 J K −1 mol −1 for the formation of LaF 2 ,(s) at 25°C. The mean activity coefficients and solubilities of LaF 2 ,(s) in NaCIO 4 solution at various ionic strengths at 25°C were evaluated.