Concentration and selection are are key to the production of spirits, and below is a short video to support your learning. How a vapour behaves above a boiling liquid is fundamentally linked to any explanation of batch distillation in pots or the function of plates in a column still.

Before you watch this video it is helpful to reiterate some key points:

A vapour is made up of gas and tiny droplets of liquid.
A liquid made up of just one fraction produces a vapour made up of one fraction.
A mixed liquid made up of two or more fractions produces a mixed vapour that is made up of the same number of fractions. The proportions of the fractions in the vapour differ from those in the liquid.
In a mixed liquid made up of ethanol and water the ethanol does not boil independently of the water when the temperature reaches 78.3°C (173°F); this quite simply does not happen. If it did happen we would all be able to make vodka on our kitchen stoves and, thankfully, we can't.

In this short video we use a simple thought experiment to show what happens to a liquid made up of only two fractions (10% ethanol and 90% water) when it is batch distilled. This highlights the key challenge that relates to distilling a fermented alcoholic liquid once and why distillers have to use other techniques as well in order to produce a spirit.

Concentration and Selection Video