Mixture Classification & Purification: Separation Techniques

Introduction to Separation Techniques

Separation techniques are methods used to separate components of mixtures. These techniques are essential in chemistry for purifying substances and analyzing mixtures.

Common separation techniques include:

• Crystallisation
• Distillation
• Filtration
• Recrystallisation
• Chromatography

Crystallisation

Crystallisation is used to purify solid substances. It involves dissolving the impure solid in a solvent and then allowing it to slowly form crystals as the solution cools.

Steps in Crystallisation

1. Dissolve the impure solid in a suitable solvent.
2. Filter the solution to remove insoluble impurities.
3. Allow the solution to cool slowly to form crystals.
4. Filter and dry the crystals.

Distillation

Distillation is used to separate mixtures based on differences in boiling points. It is commonly used to purify liquids.

Types of Distillation

• Simple Distillation: Used for separating liquids with significantly different boiling points.
• Fractional Distillation: Used for separating mixtures of liquids with closer boiling points.

Filtration

Filtration separates insoluble solids from liquids. It involves passing the mixture through a filter, which allows the liquid to pass through while retaining the solid.

Recrystallisation

Recrystallisation is a technique used to purify chemicals by dissolving both impurities and a compound in an appropriate solvent. The compound crystallizes upon cooling, leaving impurities in solution.

Chromatography

Chromatography is used to separate and analyze components of a mixture. It involves passing the mixture through a medium where components move at different rates.

Types of Chromatography

• Paper Chromatography: Uses paper as the stationary phase.
• Thin Layer Chromatography (TLC): Uses a thin layer of material on a glass or plastic plate.
• Gas Chromatography: Uses a gas as the mobile phase.