Explain the difference between the use of ‘pure’ in chemistry compared with its everyday use and the differences in chemistry between a pure substance and a mixture

Interpret melting point data to distinguish between pure substances which have a sharp melting point and mixtures which melt over a range of temperatures

Explain the types of mixtures that can be separated by using the following experimental techniques:

a) simple distillation
b) fractional distillation
c) filtration
d) crystallisation
e) paper chromatography

Describe an appropriate experimental technique to separate a mixture, knowing the properties of the components of the mixture

Describe paper chromatography as the separation of mixtures of soluble substances by running a solvent (mobile phase) through the mixture on the paper (the paper contains the stationary phase), which causes the substances to move at different rates over the paper

Interpret a paper chromatogram:

a) to distinguish between pure and impure substances
b) to identify substances by comparison with known substances
c) to identify substances by calculation and use of R_f values

Core Practical: Investigate the composition of inks using simple distillation and paper chromatography

Describe how:

a) waste and ground water can be made potable, including the need for sedimentation, filtration and chlorination
b) sea water can be made potable by using distillation
c) water used in analysis must not contain any dissolved salts