If you were performing a fractional distillation, which of the following compounds would exit the top of the distillation column first?

Question

A.)C₁₁H₂₄

B.)C₃H₈

C.)C₅H₁₂

D.)C₉H₂₀

E.) C₇H₁₆

Answer 1

Based on boiling point, (B.P.) we'd want to find the one with the lowest B.P. Using intermolecular forces as a way to predict B.P. we would say that C₃H₈ would probably have the lowest B.P. because it would have the weakest intermolecular forces. This is based on the idea that all of the compounds are hydrocarbons, are non polar and have only dispersion forces. The fewer the number of carbon atoms, the weaker the dispersion forces and the lower the B.P.