Factors affecting which separation techniques to use
- Solubility
- States
- Boiling and Melting Point
Separation methods:
- - Filtration
- - Separating funnel
- - Paper Chromatography
- - Evaporation to dryness
- - Simple distillation
- - Fractional distillation
Filtration:
A mixture of two solids can be separated by filtration if one of them is soluble in a solvent but the other is not. For example, the mixture of salt and sand can be separated by filtration using water as the solvent.
Separating funnel:
To separate two immiscible liquids, a separating funnel is used. For example, to separate oil and water the separating funnel is used.
To separate miscible liquids, they must be separated by fractional distillation. Fractional distillation can separate a solution of ethanol and water. A column, called the fractionating column is attached to the round-bottomed flask and the condenser. Many glass beads in the fractionating column provide a large surface area for vapour to condense on. Other than glass beads, a fractionating column may be filled with plate or a spiral.
During fractional distillation, the liquid with the lowest boiling point will distil over to the condenser first, the vapours of liquids with higher boiling points condense along the fractionating column and re-enter the round bottomed flask.
Chromatography :
- Separate different colour dyes
- The more soluble dyes move further up the chromatography paper than the less soluble dyes.
Evaporation to dryness :
- Solute required is left behind in the dish while the solvent escapes as water vapour
