1) Distillation of a binary mixture is carried out in a packed column. The more volatile component is transferred from the liquid to the vapour. At a vertical position in the column where the temperature is 80 C, the diffusion binary diffusion coefficient is 5 x 10-6 m2 s -1 in the vapour and 1 x 10-9 m2 s -1 in the liquid. The thickness of the laminar boundary layer is 1 mm in the liquid and 2 mm in the vapour. The liquid molar density is 50 kmol m-3. The column operates at a pressure of 1 bar, and ideal gas behaviour may be assumed.

feedback to help with cues: Q1. The overall molar concentration in the vapour had to be found using the ideal gas law (using the supplied temperature and pressure).

ANS: kg 0.0851 mol m-2 s-1; kl= 0.05 mol m-2 s-1