An insulated glass tube and condenser are mounted on a reboiler containing benzene and toluene. the condenser returns liquid reflux down the wall of the tube. at one point in the tube, the temperature is 170f, the vapor contains 30 mol% toluene, and the reflux contains 40 mol% toluene. the thickness of the stagnant vapor film is estimated to be 0.1 in. the molar latent heats of benzene and toluene are equal. calculate the rate at which toluene and benzene are being interchanged by equimolar