Distillation is the process of separating a mixture of liquids the component parts by partial evaporation and condensation of vapors. Money liquefy when cooled. So the resulting liquid is called the distillate. Boiling liquids when their vapor pressure equals the external. For pure substances boiling temperature is characteristic quantity, which depends only on the external pressure.
Distillation at normal pressure
Distillation at normal pressure to make these substances when heated, do not undergo changes and have very high boiling point. This method is widely used in laboratory practice.
Distillation at reduced pressure
Where substances have a high boiling point or undergo chemical change at this temperature, decomposition or oxidation is applied distillation under reduced pressure. This method is known by the name vacuum distillation. The apparatus for this type of distillation is considerably more complex than the previous case.
Steam distillation
Steam distillation is possible when distilled component and water are mutually insoluble. As to the apparatus for this method, it does not differ much from that for distillation at ambient temperature. You only need to add a vessel for receiving steam which is passed through the heated mixture for distillation. How is this method? It is clear that the liquid begins to boil, when the total pressure is the sum of partial pressures of individual components and water vapor equals atmospheric pressure. According to the law of Dalton, the boiling temperature of the mixture will be lower than for each of the components taken separately.
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He was also another type of distillation - fractional distillation. It is based on the different boiling temperatures of the components of the liquid. An example is the separation of gasoline ligrosin, kerosene and other oil during processing.
Destructive distillation
Destructive distillation is carried out by digestion of more complex compounds simpler. For example, in the dry distillation of coal for heating, and other wood in the absence of air is obtained solid residue and volatile products (benzene, ammonia, etc.).
1: Heat source
2: Still pot
3: Still head
4: Thermometer / Boiling point temperature
5: Condenser
6: Cooling water in
7: Cooling water out
8: Distillate / receiving flask
9: Vacuum / gas inlet
10: Still receiver
11: Heat control
12: Stirrer speed control
13: Stirrer / heat plate
14: Heating (Oil / sand) bath
15: Stirrer bar / anti-bumping granules
16: Cooling bath.
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