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[APK]

Hi,

So this is probably a very simple question but I'm just getting confused by the derivation of the Rayleigh equation for simple batch distillation.

 

My notes say that the change in composition of the liquid in the still will be a loss of d(Sx) moles of the MVC. The gain in the vapour phase will be ydS. My question, why is the gain in the vapour phase not d(Sy), won't the mole fraction of MVC in the vapour phase be changing??

 

Thanks for any help.

[breizh]

http://www.separatio...n/DT_Chp02a.htm

 

Hope this helps

Breizh