3. A mixture of benzene and p-xylene is batch-distilled at atmospheric pressure. The rate of heat input to the still is 4000kcal/hr. Individual heats of vaporization are: benzene =100kcal/kg, pxylene =85kcal/kg and the relative volatility of benzene in the mixture is 5.6. Calculate the instantaneous rate of vaporization of pxylene when the liquid in the still has 40 mole % benzene in it