Thermodynamics of ionic association 1: The standard association constant of the ion pair Li+B(OH)4−

Values of emf for the cell without liquid junction Pt, H2 (101.325 kPa) |Li2B4O7 (m1), LiCl (m2)|AgCl–Ag are reported at five temperatures from 278.15 to 318.15 K. The standard association constant of ionic pair Li+B(OH)4−, Ka, is determined by a fitting with the cell results. The dependence of pKa on temperature T is expressed in empirical equation: pKa=−131.6K/T−0.08996−1.856×10−3T/K. The other thermodynamic quantities of the association process are calculated and show that there truly exists ion pair Li+B(OH)4− and the driving force for the ion association reaction is association entropy.