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

Separation of mixtures

Since the components of a mixture are not bonded together, they can be separated without using chemical reactions.

Filtration- To separate an undissolved solid from a mixture of the solid and a liquid/solution (e.g. sand and water)

Evaporation- To separate a dissolved solid from a solution, when a solid has similar solubilities in both cold and hot solvent (e.g. sodium chloride from a solution of sodium chloride and water)

Crystallisation- To separate a dissolved solid from a solution, when the solid is much more soluble in hot solvent than cold (e.g. copper (II) sulfate from a solution of copper (II) sulfate in water)

Simple distillation- To separate a liquid from a solution (water from a solution with sodium chloride and water)

Fractional distillation- To separate two or more liquids that a miscible with each other (e.g. ethanol and water)

Paper chromatography- To seperate that have different solubilities in a given solvent (e.g. different coloured inks that have been mixed to make black ink)

Atoms 1.4 describe and explain experiments to investigate the small size of particles and their movement including: i dilution of coloured solutions ii diffusion experiments

Dilution of coloured solutions

When potassium manganate (VII) crystals are dissolved in water, a purple solution is formed. A very few tiny crystals can produce a highly intense colour. 
When this solution is diluted several times, the colour fades, but does not disappear until a lot of dilutions are made.
This indicated that there are a large number of particles of potassium manganate (VII) in a very small amount of solid. If this is true, then the particles of potassium manganate (VII) must be very tiny.

Diffusion

Particles will move to fill the space available to them. They can do this in both liquids and gases. 
An example is the diffusion of bromine from one flask to another. After five minutes the bromine gas has diffused into the left-hand flask. This happens because both air and bromine particles are moving randomly and there are large gaps between the particles. The particles can therefore easily mix together.