三斜仲钨酸铵热分解的热力学研究

Thermodynamic Study of Thermal Decomposition of Orthorhombic Ammonium Paratungstate

用热分析、Ｘ射线衍射及Ｎ含量分析研究了三斜仲钨酸铵（ＮＨ４）１０Ｈ２Ｗ１２Ｏ４２１０·Ｈ２Ｏ的热分解机理；并在ＨＴ－１０００微量热量计上，用三步量热法和适当的热化学 循环，测定了三斜仲钨酸铵热分解过程的热效应，得到了在２９８．１５ Ｋ时其热分解反应的标准 反应焓（５７６．７±１１．５） ｋＪ·ｍｏｌ－１，并由此得出三斜仲钨酸铵在２９８．１５ Ｋ时的标准生 成焓－（１５ ０２１．３±１５．７） ｋＪ·ｍｏｌ－１．

The thermal decomposed mechanism of orthorhombic ammonium paratungstate,(NH4)10H2W12O4210H2O,was investigated by DAT,XRD and analysis of N content.The heat of the thermal decomposition of orthorhombic ammonium paratungstate was measured in a HT-1 000 microcalorimeter by three vstep calorimetry and suitable thermochimic cycle.The standard enthalpy of reaction at 298.15 K for the thermal decomposition was obta ined as (576.7±11.5) kJ·mol-1,and then,the standard enthalpy of formati on at 298.15 K for monoclinic ammonium paratungstate was obtained as -(15 021.3 ±15.7)kJ·mol-1.