| 硼砂水溶液的低温热容及热化学性质研究 |
| Low-Temperature Heat Capacities and Thermodynamic Properties of Aqueous Na2B4O7 Solution |
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| 摘要: 利用精密绝热量热仪测定了0.033 55 mol·kg-1的硼砂水溶液在78~351 K温区的热容，从实验热容测定结果得到了该水溶液的凝固点为272.905 K。用最小二乘法将实验热容值对温度进行拟合，建立了该溶液的热容随温度变化的多项式方程。根据热力学函数关系式，用此多项式方程进行数值积分, 获得了以298.15 K为基准的该溶液在 80~350 K 温区每隔5 K的热力学函数值，并计算出摩尔熔化焓和熔化熵分别为4.536 kJ·mol-1和16.22 J·K-1·mol-1。根据溶液凝固点降低值，计算出了该溶液的活度为0.997 63。 |
| 关键词: 硼砂水溶液 低温热容 热力学函数 绝热量热 |
| 基金项目: |
| Abstract: The molar heat capacities of aqueous Na2B4O7 solution with concentration of 0.033 55 mol·kg-1 were measured by a precision automated adiabatic calorimeter in the temperature range from 78 K to 351 K. The fusion transition at T=272.905 K was observed from the heat capacity measurements. According to the polynomial equations of heat capacity as a function of temperature and thermodynamic relationship, the thermodynamic functions (HT-H298.15K ) and (ST-S298.15 K) of the aqueous borax decahydrate solution were derived in the temperature range from about 80 to 350 K with an interval of 5 K. The molar enthalpy and entropy of the phase transition were determined to be 4.536 kJ·mol-1 and 16.62 J·K-1·mol-1. The activity of the solution was determined to be 0.997 63 by using the freezing point depression of the solution based on the liquid-solid phase equilibrium rule. |
| Keywords: aqueous Na2B4O7 solution low-temperature heat capacity thermodynamic function adiabatic calorimetry |
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| 摘要点击次数: 1965 |
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| 孟庆芬,谭志诚,董亚萍,冯海涛,李 武.硼砂水溶液的低温热容及热化学性质研究[J].无机化学学报,2010,26(8):1333-1338. |
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