Common Separation Techniques
In Chemistry, separation techniques are methods used to separate and purify components from a mixture, by making use of the differences in their properties (e.g. solubility, phase, etc.). Some common separation techniques include:
1. Filtration
To separate a solid from a liquid.
2. Evaporation
To obtain a solid from a solution. This solid must be stable to heat. e.g. sodium chloride.
3. Crystallization
To separate a solid from a solution.
4. Distillation
To obtain a solvent from a solution.
5. Fractional distillation
To separate miscible liquids with different boiling points. The liquid with the lowest boiling point will be separated first.
6. Using a separating funnel
To separate immiscible liquids. The denser liquid is found at the lower portion of the separating funnel, and can be obtained by opening the tap at the bottom of the funnel.
7. Chromatography
To separate the different components of ink, dyes, etc. This separation method is achieved by the different solubility of the solutes in the solvent. The most soluble solute will travel the furthest from the starting point.
Test for purity
We can use melting/ boiling point to test for purity:
A pure substance has a fixed melting and boiling point.
An impure substance will melt and/or boil over a range of temperature.