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How many moles are there in the vapor phase?
How much heat had to be added to the vessel contents (neglect that heat that goes to
heating the vessel itself) to reach this condition?
The Txy diagram on the following page is for the benzene-toluene system.
The vapor composition must lie along the dew point curve of the Txy diagram as shown.
Thus the liquid composition is xBenz = 0.23. This tie line corresponds to a temperature of
Applying the lever rule along the tie-line gives 100 0.30
0.42 0.368 0.23
36.8 To do this create an enthalpy input/output table as shown below
Toluene (v) nin (moles) (kJ/mole) nout (moles) (kJ/mole) Initially all of the materials were liquid so the number of moles can be found from the
problem statement. For the out side of the table take the composition times the number
of moles in the vapor to get the moles of that component in the vapor and subtract this
number from the total number of moles to get the moles in the liquid. Thus for benzene
the number of moles in the vapor would be 0.42 (36.8) = 15.5 mole and the number of
moles in the liquid would be 30 – 15.5 = 14.5 mole. This gives a table that looks like Compoun...
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- Fall '08
- Chemical Engineering