explain what is meant by the purity of a substance, distinguishing between the scientific and everyday use of the term ‘pure’

use melting point data to distinguish pure from impure substances

calculate relative formula masses of species separately and in a balanced chemical equation

the definition of relative atomic mass, relative molecular mass and relative formula mass

deduce the empirical formula of a compound from the relative numbers of atoms present or from a model or diagram and vice versa

explain that many useful materials are formulations of mixtures

alloys

describe, explain and exemplify the processes of filtration, crystallisation, simple distillation, and fractional distillation

knowledge of the techniques of filtration, crystallisation, simple distillation and fractional distillation

describe the techniques of paper and thin layer chromatography

using aqueous and non-aqueous solvents and locating agents

recall that chromatography involves a stationary and a mobile phase and that separation depends on the distribution between the phases

identification of the mobile and stationary phases

interpret chromatograms, including measuring R_f values

the recall and the use of the formula

suggest suitable purification techniques given information about the substances involved

suggest chromatographic methods for distinguishing pure from impure substances

paper, thin layer (TLC) and gas chromatography