Understanding the Principles Behind Distillation Essay Example

than initially perceived.

Despite common misconceptions, mixing two different liquids together does not result in each boiling at its normal boiling point, producing a pure distillate. This is even true in an idealized system with liquids of similar chemical structure. The ideal distillation process is governed by Raoult’s Law and Dalton’s Law. Raoult’s Law indicates that the partial vapor pressure of a component in a mixture is equal to the vapor pressure of the pure component at that temperature multiplied by its mole fraction in the mixture. Meanwhile, Dalton’s Law states that the total vapor pressure is the sum of the vapor pressure of each component in the mixture. Therefore, when an ideal blend of liquids is heated, each component’s vapor pressure will increase, leading to a rise in the total vapor pressure.

When the total vapor pressure is equivalent to the ambient pressure, boiling takes place. A mixture of two mutually soluble liquids in a 50:50 ratio will boil at a temperature that is halfway between the boiling points of the pure substances. However, this type of ideal scenario is rarely encountered as most liquids have varying chemical structures which result in slight solubility and changes in volatility. Therefore, there are notable deviations from Raoult's Law's predicted behaviors.

When a mixture of alcohol and water is heated, an azeotrope is produced, which happens when the mixed substances have a lower boiling point than if they were pure. This process often involves distillation, commonly used in college-level chemistry courses. It should be emphasized that the vapor of the mixture will contain more of the volatile component.

While distillation cannot achieve complete purity, it can effectively purify a distillate.