One thousand kilograms per hour of a mixture containing equal parts by mass of ethanol and water is distilled. Product streams leave the top and the bottom of the distillation column. The flowrate of the bottom stream is measured and found to be 673 kg/h, and the overhead stream is analyzed and found to contain 96 wt% ethanol. Find the flowrates of all components in all streams.

You correctly claimed that we can find the flowrates of water and ethanol in the overhead stream from the information given in the problem statement. Generally,

Foverhead,water = Foverhead,total * xoverhead,water

Foverhead,ethanol = Foverhead,total * xoverhead,ethanol

So all we need to do is figure out the compositions (mass fractions) of water and ethanol in the overhead stream in order to fill in the entire top row.

What is the mass fraction of water in the overhead stream?

What is the mass fraction of ethanol in the overhead stream?

Streams\mass flow rate Total Ethanol Water
Feed 1000 500 500
Overhead 327 Foverhead,ethanol Foverhead,water
Bottoms 673 Fbottoms,ethanol Fbottoms,water




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