Plotting 1/(y - x) versus x and integrating graphically between the limits of 0.06 and 0.18 for x, the area under the curve is found to be 0.358. Then, ln (M, /M) = 0.358, from which Ms = 100/1.43 = 70.0 mol. The liquid remaining consists of (70.0)(0.06) = 4.2 mol of ethanol and 65.8 mol of water. By material balance, the total distillate must contain (18.0 - 4.2) = 13.8 mol of alcohol and (82 - 65.8) = 16.2 mol of water. Total distillate is 30 mol, and distillate composition is 13.8/30 = 0.46 mole fraction ethanol.
The simple batch still provides only one theoretical plate of separation. Its use is usually restricted to preliminary work in which products will be held for additional separation at a later time, when most of the volatile component must be removed from the batch before it is processed further, or for similar noncritical separations.
Was this article helpful?