Distillation is a powerful method to separate the constituents of a homogenous mixture. The distillation technique takes advantage of the difference in boiling temperatures. The reaction mixture is heated to the boiling temperature of the most volatile liquid. The most volatile substance evaporates first and vapor is formed in a distillation apparatus. The vapor is then condensed back down to liquid after it passed down the condenser and collected at the end in the collecting flask. This setup is called simple distillation. It works well to separate a mixture that contains one volatile component.

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, used to increase the temperature of our initial mixture. 4, A condenser, that will separate liquids with different condensation points. 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 collection flask, where our purified mixture will be collected.

Figure 1. Distillation apparatus. 1. Thermometer; 2. Distillation flask; 3. Heating mantle; 4. Condenser; 5. Cooling water out; 6. Cooling water in; 7. Collecting flask.

The condenser, distillation flask, and thermometer are connected by an adapter (3-way adapter or Y-arm). The mercury bulb of the thermometer is placed in this adapter, at the opening that leads to the condenser, so the bulb is surrounded by the hot vapor, which is crucial for reliable temperature readings. It's possible to connect a source of reduced pressure to the distillation set up, to achieve vacuum distillation

The simple distillation is unable to result in pure substance if the mixture includes several volatile components. A more sophisticated distillation is required to obtain the pure substance from a mix with various volatile constituents.