Gas chromatography is able to seperate cyclohexane & isopropyl alcohol even though distillation can't. Why?

Answer 1

The conditions are different.

Cyclohexane has a boiling point of 80.74 °C and isopropyl alcohol has a boiling point of 82.3 °C which is very close. Separating by distillation would be difficult as both of the liquids would have some vapor pressure at either temp.

Gas chromatography uses (or can use) a stationary phase which has a high polarity allowing the cyclohexane to travel through while hindering the alcohol (which would come out of the column later). The separation is almost always 100 percent.