Thermodynamic Study of the Aqueous Rubidium and Manganese Bromide System

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• 作者：C. Balarew ; D. Rabadjieva ; S. Tepavitcharova ; C. Christov and O. Angelova
• 关键词：Pitzer model ; rubidium and manganese bromide ; solubility diagram ; double salt RbBr · ; MnBr2 · ; 2H2O ; Gibbs energy ; enthalpy of formation
• 刊名：Journal of Solution Chemistry
• 出版年：1999
• 出版时间：1999
• 年：1999
• 卷：28
• 期：7
• 页码：949-958
• 全文大小：513 KB

文摘

Crystallization of 2RbBr · MnBr₂ · 2H₂O, the only double salt obtained under standard conditions from saturated aqueous rubidium–manganese bromide solutions, was theoretically predicted using the hard and soft Lewis acids and bases concept and Pauling''s rules. The RbBr—MnBr₂—H₂O system was thermodynamically simulated by the Pitzer model assuming a solubility diagram of three branches only: RbBr, 2RbBr · MnBr₂ · 2H₂O and MnBr₂ · 4H₂O. The theoretical result was experimentally proved at 25°C by the physicochemical analysis method and formation of the new double salt 2RbBr · MnBr₂ · 2H₂O was established. It was found to crystallize in a triclinic crystal system, space group –P1, a = 5.890(1) Å, b = 6.885(1) Å, c = 7.367(2) Å, = 66.01(1)°, = 87.78(2)°, = 84.93(2)°, V = 271.8(1) Å3, Z = 1, D_x = 3.552 g-cm–3. The binary and ternary ion interaction parameters were calculated and the solubility isotherm was plotted. The standard molar Gibbs energy of the synthesis reaction, _rG_mo, of the double salt 2RbBr · MnBr₂ · 2H₂O from the corresponding simple salts RbBr and MnBr₂ · 4H₂O, as well as the standard molar Gibbs energy of formation, _fG_mo, and standard molar enthalpy of formation _fH_mo of the simple and double salts were calculated.