五水合五硼酸钠溶解热测定及其热力学性质

Dissolution Enthalpy and Thermodynamic Properties of NaB5O8·5H2

中文关键词:  溶解焓  硼酸钠  标准生成焓  标准生成熵  标准吉布斯自由能

英文关键词:Dissolution enthalpies  Sodium borates  Standard enthalpy of formation  Standard entropy of formation  Standard Gibbs free energy(continued on page 100)

中文摘要:

      不同形态硼酸盐焓、熵、吉布斯自由能等热力学参数极为缺乏，其准确测定对丰富和发展盐湖硼酸盐化学理论至关重要。采用微量热计测定了五水合五硼酸钠(NaB5O8·5H2O)溶解热。根据设计的热化学循环和热力学基本公式，获得了NaB5O8·5H2O在29815 K下标准生成焓(△Hθf，NaB5O8·5H2O，-5 189.482 0 kJmol-1)、标准生成熵(△Sθf，NaB5O8·5H2O，701.272 8 Jmol-1K-1)、标准生成吉布斯自由能(△Gθf，NaB5O8·5H2O，-5 398.566 5 kJmol-1)等热力学参数。这些基础热力学参数的获得对丰富无机盐热力学数据和促进盐湖资源综合利用具有重要意义。

英文摘要:

      Thermodynamic parameters of different borates，such as the dissolution enthalpy(△Hs)，the standard enthalpy of formation(△Hθf)，the standard entropy of formation(△Sθf)and the standard Gibbs free energy(△Gθf)are essential to enrich and develop the boron chemistry theory of salt lakes In the present work，the dissolution enthalpy(△Hs)of sodium pentaborate pentahydrate(NaB5O8〖DK〗·5H2O)at 29815 K and 101.325 kPa was measured using microcalorimeter Based on the designed thermochemical cycles and the basic formulae of thermodynamics，the standard enthalpy of formation(△Hθf)，the standard entropy of forma1tion(△Sθf)and the standard Gibbs free energy(△Gθf)of NaB5O8·5H2O were obtained for the first time，and the results are in order with -5 189.482 0 kJ SymbolWC@mol-1，701.272 8 J SymbolWC@mol-1SymbolWC@K-1，-5 398566 5 kJ SymbolWC@mol-1，respectively These basic thermodynamic parameters obtained in this work are of great significance in enriching the thermodynamic data of inorganic salts and promoting the comprehensive utilization of salt lake resources