The standard molar enthalpies of formation of zirconium sulphate and its crystal hydrates

• Published in: The Journal of chemical thermodynamics 1983-01, Vol.15 (6), p.523-529
• Main Authors: Melnikova, V.M, Efimov, M.E, Vasin, S.K, Medvedev, V.A
• Format: Article
• Language: English
• ISSN: 0021-9614; 1096-3626
• DOI: 10.1016/0021-9614(83)90051-4

The enthalpies of solution of α-Zr(SO 4) 2(c), Zr(SO 4) 2·4H 2O(c), ZrCl 4(c), KCl(c), K 2SO 4(c), and H 2O(l) in 3.0 mol·dm −3 HCl(aq) were measured. The measurements were carried out in the 100 cm 3 reaction vessel of the isoperibol calorimeter LKB-8700. The following values were calculated from these measurements: Δ f H m o{α-Zr(SO 4) 2, c, 298.15 K) = −(2244.2 ± 2.2) kJ·mol −1; Δ f H m o{Zr(SO 4) 2·4H 2O, c, 298.15 K} = −(3469.3 ± 2.7) kJ·mol −1. α-Zr(SO 4) 2 includes an excess of 0.03 mol of SO 3 and in this paper α-Zr(SO 4) 2 means Zr(SO 4) 2·0.03SO 3. Using literature enthalpies of solution of Zr(SO 4) 2(c) and of its mono- and tetra-hydrates in water, the value: Δ f H m o{Zr(SO 4) 2·H 2O, c, 298.15 K} = −(2576±6) kJ·mol −1 was calculated.