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• 作者：Aiqun Yuan ; Jian Wu ; Lijuan Bai ; Shaomei Ma ; Zaiyin Huang ; Zhangfa Tong
• 刊名：Journal of Chemical & Engineering Data
• 出版年：2008
• 出版时间：May 2008
• 年：2008
• 卷：53
• 期：5
• 页码：1066 - 1070
• 全文大小：108K
• 年卷期：v.53,no.5(May 2008)
• ISSN：1520-5134

文摘

Ammonium/transition metal phosphate monohydrate NH₄MPO₄·H₂O (M = Mn²⁺, Co²⁺, Ni²⁺, Cu²⁺) compounds were synthesized by solid-state reaction at low temperature and characterized by X-ray diffraction (XRD), FT-IR, and chemical analysis. Based on Hess’s law, the thermochemical cycles were designed for measuring the dissolution enthalpies of reactants and products using a solution-reaction isoperibol calorimeter at 298.15 K. From the dissolution enthalpies, the molar enthalpies of the five reactions designed were calculated individually. With these data and other auxiliary theromodynamic data, the standard molar enthalpies of formation of the title compounds were concluded as: Δ_fH_m^Θ[NH₄MnPO₄·H₂O] = (−1925.01 0.25) kJ·mol⁻¹, Δ_fH_m^Θ[NH₄CoPO₄·H₂O] = (−1754.91 0.43) kJ·mol⁻¹, Δ_fH_m^Θ[NH₄NiPO₄·H₂O] = (−1755.48 0.39) kJ·mol⁻¹, and Δ_fH_m^Θ[NH₄CuPO₄·H₂O] = (−1636.41 0.36) kJ·mol⁻¹.