Relative Volatility in One Theoretical Stage

The separation power in a distillation column comes from the thermodynamic vapor-liquid equilibrium relative volatility, the number of theoretical stages achieved by the column, and the 

X = mole fraction in liquid phase y = mole fraction in vapor phase subscript 1 = component 1 subscript 2 = component 2 

For example, when 4.88 wt% ethanol in water is in equilibrium with 35.58 wt% ethanol in water vapor at atmospheric pressure, the relative volatility, a, is equal to (35.58/64.42)/ (4.88/95.12) = 10.77. 

Stage No. Mol% C6 in Liquid Mol% C6 in Vapor Total Separation Power 

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