硼酸盐水溶液热力学研究——Ⅱ.H_3BO_3-LiB(OH)_4-LiCl-MgCl_2体系

Study on the Thermodynamics of Aqueous Borate Solution——Ⅱ. The System H_3BO_3-LiB(OH)_4-LiCl-MgCl_2

在278.15～318.15K下,测定了无液接电池(A),Pt,H_2|B(OH)_3(m_1),LiB(OH)_4(m_2).LiCl-(m_3),MgCl_2(m_4)|AgCl,Ag和电池(B),Pt,H_2|B(OH)_3(m_1),LiB(OH)_4(m_2),MgCl_2(m_4)|AgCl,Ag的电动势.利用Debye-Hückel外推法和多项式拟合法确定了硼酸镁离子对[MgB(OH)_4^+]缔台常数pK_T,并得到了经验方程pK_T=A_1+A_2/T+A_3T以及缔合过程的其他各标准热力学量,同时指出缔合熵是形成[MgB(OH)_4^+]离子对的推动力.

The electromotive force measurements have been made with the cells Pt, H2|B(OH)3-(m1), LiB(OH)4(w2), LiCl(m3), MgCl2(m4)| AgCl, Ag and Pt, H,| B(OH)3(m1), LiB(OH)4(m2), MgCl2(m4)| AgCl, Ag over the temperature range 278.15-318.15K. The results have been used to determined the standard association constants of ionic pair [MgB(OH)4+], Kr. An empirical equation, pKT=A1+A2/ T+A3T, was obtained, the other thermodynamic quantities of ionic association process were calculated and discussed. An important conclusion was drawed, that is, the association enthopy is the driving force for the ion association reaction.