A NEW EQUILIBRIUM CELL WITH VARIABLE CELL-VOLUME FOR STATIC VAPOR-PRESSURE MEASUREMENTS

In this work, we present a new equilibrium cell with variable cell vol ume for static vapour-pressure measurements. This new cell allows a re duction in the time required to reach vapour-liquid equilibria of syst ems showing strong deviations from ideality. For the system 2-butanone + water, the time to reach equilibrium is reduced from more than 8 h down to 1.5 h. To achieve this, the components are mixed in the liquid phase before the formation of a vapour phase is allowed. A piston mov ing into the cell is used to condense the vapour. After mixing the liq uid components, the piston is retracted and the equilibrium vapour all owed to form. Isothermal total-pressure data for the systems 2-butanon e + water and cyclohexane + toluene determined with this new cell are presented.