CALCULATION OF OSMOTIC PRESSURE USING A CLOSED SYSTEM MODEL

In this work we have used a closed system model to derive an analytical equation for the osmotic pressure of two component electrolyte and non-electrolyte solutions. In order to do so, we have used an equation of state, known as the dense system equation of state (DSEOS), for the model system. Based on the model, a new definition is given for the osmotic pressure of a closed system. Good agreement between the calculated and experimental osmotic pressure is obtained. Using the results obtained for the osmotic pressure along with some exact thermodynamic arguments, we have calculated the solvent activity for some electrolyte and nonelectrolyte solutions. The calculated activities are found to be in good agreement with the experiment, in such a way that for the NaCl solutions the deviations for the calculated activities are less than 0.02% for solutions up to six molal