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化学学报
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化学学报 ›› 1999, Vol. 57 ›› Issue (9): 992-996. 上一篇    下一篇

研究论文

硼酸盐水溶液热力学研究: 4.离子对[CaB(OH)~4]^+标准缔合 常数的确定

孙柏;宋彭生;杨家振;邓敏;高岩岩   

  1. 中国科学院青海盐湖研究所.西宁(810008);辽宁大学化学系.沈阳(110036)
  • 发布日期:1999-09-15

The thermodynamics of aqueous borate solutions: 4. The standard association constant of ion pair [CaB(OH)~4]^+

Sun Bai;Song Pengsheng;Yang Jiazhen;Deng Min;Gao Yanyan   

  1. Qinghai Inst Salt Lake, CAS.Xining(810008);Liaoning Univ, Dept Chem. Shenyang(110036)
  • Published:1999-09-15

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在温度为278.15-318.15K范围内测定了含有不同Li~2B~4O~7和CaCl~2浓度测试液的无液接电池:Pt,H~2(101.325kPa)|Li~2B~4O~7(m~1),CaCl~2(m~2)|AgCl-Ag的电动势E(V)。在Pitzer电解质溶液理论基础上,用线性外推法确定离子对[CaB(OH)~4]^+的标准缔合常数K~d,并得到K~d随温度T变化的经验公式:pK~d=0.6857-359.72/T-4.632×10^-^3T。同时计算得到了离子对缔合过程的热力学函数,指出形成该离子对的推动力是缔合熵。

关键词: 硼酸盐, 钙化合物, 离子对, 电动势, 缔合常数, 缔合熵, 热力学, 溶液理论

Emfs for the cell without liquid junction: Pt, H~2 (101.325kPa) |Li~2B~4O~7(m~1), CaCl~2(m~2)|AgCl-Ag are reported at five temperatures from 278.15 to 318.15K. The standard association constant of ionic pair [CaB(OH)~4]^+, K~d is determined by fitting to the cell results. The dependence of pK~d on temperature T is expressed by an empirical equation: pK~d=0.6857-359.72/T-4.632×10^- ^3T. The other thermodynamic quantities of the association process are also calculated. The results show that the driving force for the ion association reaction is association entropy.

Key words: BORATES, CALCIUM COMPOUDS, ION PAIRS, ELECTROMOTIVE FORCES, ASSOCIATION CONSTANT, THERMODYNAMICS, SOLUTION THEORY

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