One thousand kilograms per hour of a mixture of benzene (B) and toluene(T) that contains 50% benzene by mass are seperated by distillation into two fractions. The mass flow rate of benzene in the top stream is 450 kg B/h, and that  of toluene in the bottom stream is 475 kg T/h.  The operation is at steady state.  Write balances on benzene and toluene to calculate the unknown component flow rates in the output streams.

Now we are confronted with what else we can do now that we have filled in all the given flowrates into the problem statement. Recall from our interrelationships page that we can use the relationship between the total mass flowrate and the mass fraction of a component in a stream to find the flowrate of the component. Just as a reminder:

Fi = Ftotalxi

Take a minute to think about the information that you could use next now that we remember this trick.

Streams\mass flow rate Total Benzene Toluene
Feed 1000
Overhead
450
Bottoms
475



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