A rectifying column consists of a tube arranged vertically and supplied at the bottom with a mixture of benzene and toluene as vapor. At the top, a condenser returns some of the product as a reflux...

Extracted text: A rectifying column consists of a tube arranged vertically and supplied at the bottom with a mixture of benzene and toluene as vapor. At the top, a condenser returns some of the product as a reflux which flows in a thin film down the inner wall of the tube. At one point in the column, the vapor contains 60 mol% benzene and the adjacent liquid reflux contains 51 mol% benzene. The temperature at this point is 92°C. Assuming the diffusional resistance to vapor transfer to be equivalent to the diffusional resistance of a štagnant vapor layer 0.5 mm thick, calculate the rate of interchange of benzene and toluene between vapor and liquid. The molar latent heats of the two materials can be taken as equal. The vapour pressure of toluene at 92°C is 44.0 kN/m2 and the diffusivity of the vapors is 0.053 cm?/s.