1.7 describe experimental techniques for the separation of mixtures, including simple distillation, fractional distillation, filtration, crystallisation and paper chromatography

Simple Distillation:

The separation of a dissolved solid from a liquid. This is done by evaporating the liquid and the solid will remain.

Fractional Distillation:

The separation of a mixture of gases and/or liquids. This is done using a fractional column. The mixture is heated until everything is in the gaseous state. The gases then rise up the column where the temperature constantly decreases; as the gases have different boiling points, they will condense at different heights in the tube and are then collected.

e.g. mixture of hydrocarbons in crude oil are separated:

Filtration:

Usually used to separate liquids from non-dissolved solids. Filtration is where there is a barrier preventing the non-dissolved solids from passing while the liquid can.

e.g. a mixture of sand and water through filter paper. The sand gets caught in the filter paper while the water passes through.

Crystallisation:

A solution is heated allowing some of the solvent to evaporate. The solution is then left to cool; during this time crystals will begins to form.

Paper Chromatography:

Usually used to separate the different types of ink. Using a pencil (as it doesn't dissolve) draw a base line on the chromatography paper. Then draw a dot using the ink you want to separate. The chromatography paper is then placed in a solvent. The solvent will climb up the paper carrying with it the ink. The different types of ink will stop at different heights on the paper due to their different sizes.