Question

why are you able to collect a more concentrated sample of ethanol from a mixture of water and ethanol using fractional distillation

Answer 1

Fractional Distillation uses the differences in boiling points to separate liquids that are hard to separate manually (like with a pipette or filtration).

Water boils at 100°C, while ethanol boils at around 78-79°C. So, if you heated the solution to 78-79°C, the ethanol would boil off and the water would stay in its liquid form. The Ethanol can be collected in a more concentrated form this way.

Hope this helps!