# Relative Volatility in a Non-Ideal System

## Main Question or Discussion Point

May I Ask Another Ques?

Because I want to know the distribution of component of a non-ideal multicomponent mixture in a distillation column, I had calculated the activity coefficient for a particular multicomponent system at a temperature, lets say 60 C.
Thus I can obtain its relative volatility afterwards.

The question is would the relative volatility of this substance change or stays approximately the same when the T is being increased or decreased by let's say 30 C , considering that this system is a non ideal VLE system? I am doing this part because I wish to know its overhead temperature and distillate's temperature...

If the answer is "No"..I have to recalculate the activity coefficient but this is rather tedious as I am using UNIFAC method to calculate activity coefficient..so can I just assume that the changes in relative volatility is slight upon changes in temperature?

## Answers and Replies

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Chestermiller
Mentor
The thing to do is to do some scouting calculations using UNIFAC for some estimated conditions to get an idea how it plays out. Of course, using computers to do the detailed calculations does not require one to assume constant relative volatility.