Organic Chemistry

Question 1

Relationship between boiling point and molecular size

Answer 1

Topic sentence

the greater the total intermolecular force between molecules, the greater the amount of energy is required to OVERCOME(boil) / STRETCH(melt) them which results in a greater boiling point.

Alkanes

alkanes are non-polar molecules therefor their only intermolecular force is dispersion force.

Dispersion force

dispersion force increases with increasing molecular mass, because there’s more electrons to displace and create a greater dipole. As a result, more energy is needed to overcome the dispersion force.

Link to graph

this is evident in the graph as boiling point is increasing LINEARLY as the amount of carbons increase (molecular mass).