A group of the same atoms in a substance that is not mixed with anything else. Something that contains one compound or element throughout.
Pure substances
Melt and boil at one temperature
The temperature stays the same until all the solids have melted or boiled
Impure substances
Melt and boil at more than one temperature
Paper Chromatography
Used to separate colourings
Retention factor (Rf)
Distance travelled by substance divided by the distance traveled by solvent
Filtration
Separation technique used to separate a solid that hasn't dissolved in a liquid. A filter paper is placed inside a glass funnel and a container is put beneath the filter.
Filtration
Filtrate
Glass Funnel
Solid Residue
Filter Paper
Crystallisation
Technique used to separate a solid that has dissolved in a liquid and make a solution
Crystallisation
Slow Formation = Large Crystals
Fast Formation = Small Crystals
Distillation
Process used to separate a pure liquid from a mixture of liquids. It works when the liquids have different boiling points.
Distillation
Commonly used to separate ethanol - the alcohol in alcoholic drinks - from water
