Abstract: Activity coefficients and osmotic coefficients of sodium tetraphenylborate in the aqueous solution with different concentration were measured in the temperature regions of 288. 15-318. 15 Kby the isopiestic method. The results show that the logarithms of activity coefficients of sodium tetraphenylborate have a linear relationship with temperature. Furthermore, the excess Gibbs free energy, relative partial molar enthalpy, relative partial molar heat capacity of sodium tetraphenylborate are calculated. The formula used to estimate the values of thermodynamic functions of sodium tetraphenylborate are given by the curcve fitting on microcomputer.

Key words: Tetraphenylborate, Activity coefficients, Osmotic coeffients, Thermodynamic properties