A novel osmotic pressure route to the activity coefficient of a molecule in a solution

It is proposed that a powerful and convenient method of measuring the activity coefficient of a molecular species in a liquid mixture is to do an osmosis experiment. The only information required is the equation of state of the pure solvent. The procedure has been tested and verified by a modified GEMC simulation. The results are compared with van der Waals one-fluid theory, which is found to be remarkably good.