An apparatus for the measurement of vapor pressure of solutions by static method is established. It includes an equilibrium cell

mercury manometer

degassing vessel and high vacuum device. With these apparatus

the vapor pressure of acetic acid-water binary mixture over the temperature range 25-75℃ were determined. In order to get complete isothermal vapor liquid equilibrium data

the equilibrium vapor compositions were calculated by a direct thermodynamic method developed by us formerly. The vapor phase association has been taken into consideration in calculations.The results are presented in tabular form. A thermodynamically derived polynomial formula correlating the activity coefficients and temperatures has been developed to fit the experimental results. The parameters of the polynomials were obtained by least square method. With the use of these parameters and extrapolating to ordinary pressure

the prediction of bubble points and vapor compositions are in good agreement with the ordinary isobaric experimental data reported in literatures.These parameters can be recommended for the purpose of practical vapor liquid equilibrium calculations over the wide range from low pressure to ordinary pressure.