Thermodynamische Untersuchungen an wäßrigen Lösungen von (NH

Thermodynamics of formation of double salts and mixed crystals from aqueous solutions

“…Note that in constructing the mixed solutions {m 1 FeSO 4 + m 2 Fe 2 (SO 4 ) 3 }(aq) and {m 1 K 2 SO 4 + m 2 Fe 2 (SO 4 ) 3 }(aq) model [65] the pure electrolyte Al 2 (SO 4 ) 3 (aq) parameters from references [57,59] are accepted as an approximation for ferric sulfate binary parameters {valid up to %1 mol kg À1 of Fe 2 (SO 4 ) 3 }. Simulation of the binary solutions of alkali selenates and sodium bichromate was performed on the basis of experimental osmotic coefficients data obtained by us using the isopiestic method [24,26,36,37,56,61]. The comprehensive description of the isopiestic method for determination of a w , and/or / is given in references cited above.…”

Thermodynamic study of (m1Cs2SeO4+m2NiSeO4)(aq)wheremdenotes molality atT= 298.15 K

“…The salts obtained were recrystallized twice with distilled water at room temperature in a desiccator above concentrated sulfuric acid and dried in air. (1,2,(4)(5)(6) The osmotic coefficients of the Cs 2 SeO 4 (aq) solutions were determined by the isopiestic method described by Ojkova et al, (1,4) Christov et al, (2) and Stoilova et al (5) The solutions were prepared by the gravimetric method. The salts were weighed with an accuracy of ±1 · 10 −5 g giving, after the addition of 3 ml of water, a solution of the desired concentration.…”

“…The concentrations in table 1 are accurate to within ±0.2 per cent or better. The osmotic coefficients φ of Cs 2 SeO 4 (aq) were calculated from equation (1): (2,4) …”

“…(15) It has been shown that Pitzer equations can describe the properties of binary (1,2,4,13) and multicomponent (16,17) solutions in which phases with a constant composition (simple and double salts) (16)(17)(18)(19)(20) and solid solutions (3,5) crystallize.…”

“…Comparative analysis of the ternary selenate solutions of the type (m 1 M 2 SeO 4 + m 2 MeSeO 4 )(aq) where M denotes Na, K, NH 4 , Rb, or Cs, Me denotes Mg, Ni, Co, Zn, Fe, Cu, Mn, or Cd, and m denotes molality, with the corresponding sulfate solutions (m 1 M 2 SO 4 + m 2 MeSeO 4 )(aq) shows that in most of the cases double salts with the stoichiometric composition 1 : 1 : 2, 1 : 1 : 4 and 1 : 1 : 6 crystallize from the saturated ternary solutions. (2) The crystallization or its absence from the corresponding sulphate or selenate solution of a double salt and its stoichiometric composition depend on the ion radii of the cations (M + and Me 2+ ) and of the sulfate and selenate ions.…”