Distillation is a powerful method that can separate the fractions of a homogenous mixture (i.e., mixed or blended well together) of liquids. The method exploits the difference between the fractions' boiling temperatures.

When heating the mixture, the most volatile liquid will evaporate first and leave the distilling flask. In simple distillation, this vapor then passes through a condenser before being collected at the end in the receiving flask.

If the mixture includes components with similar boiling points, simple distillation is not enough to separate the substances. In such cases, we do fractional distillation by adding a fractionating column between the distilling flask and the distilling head. The fractionating column makes the mixture go through multiple cycles of evaporation and condensation before entering the condenser.

The representation of a distillation apparatus with all its components. It consists of 
1: a thermometer to measure the temperature
2: a distillation flask where we have our initial mixture
3: a heating mantle to increase the temperature of the initial mixture
4: a condenser that condenses the vapors leaving the distilling flask
5: a cooling water output to get rid of the cold water pumped into the condenser
6: a cooling water input that will provide a constant supply of cold water to the condenser
7: A receiving flask where one component at a time will be collected.

Figure 1: Distillation apparatus. 1. Thermometer held by a distilling head; 2. Distillation flask; 3. Heating mantle; 4. Condenser; 5. Cooling water out; 6. Cooling water in; 7. Receiving flask.