In school science, the condenser is often used to separate alcohol and water mixtures. In this case, the mixture is heated in a flask connected to the condenser. Because the boiling point of alcohol is less that of water, the alcohol vapours leave the mixture upon heating and enter the internal pipe of the condenser. The water cools the vapours and pure alcohol leaves the bottom of the pipe.

Cold water should always be pumped through the bottom tube of the condenser jacket and out of the top tube. This increases the efficiency of the device.