Section A: Key Vocabulary Subject: Chemistry Year 10 Autumn Term—C2.1 Purity and Separating Mixtures Tier 3 vocabulary Definition Relative atomic The mean mass of an atom of an element Section B: Microscopes Section C: Diagrams mass (Ar) compared to 1/12 the mass of a 12C atom. Relative formula The mean mass of a unit of a substance Relative formula mass and Empirical formulae Filtration and Crystallisation mass (Mr) compared to 1/12 the mass of a 12C atom. Empirical formula Formula showing the simplest whole- Calculating relative formula mass (e.g. H2O) : (n) number ratio of the atoms of each element 1. Write down Ar values of elements in the compound (this in a compound. Pure substance Consisting of just one type of element or is the larger of the two numbers next to (n) compound. An elements symbol): H = 1.0, O = 16.0 Filtrate (n) Liquid that passes through the filter during filtration. 2. Work out the number of atoms of each element: • Filtration separates any insoluble substances Residue (n) Insoluble material left in the filter paper H = 2, O = 1 from a liquid/solvent. during filtration. 3. Multiply the number of each atom by its Ar value and • Crystallisation separates a solute from a Saturated A solution containing the maximum mass of add these together: Mr = (2 x 1.0) + (1 x 16.0) = 18.0 solution. solution (n) solute possible at a given temperature. Liebig condenser Apparatus that can cool and condense a Simple and Fractional distillation (n) substance. Calculating an empirical formula (e.g. Butene, C4H8) Fraction (n) In Chemistry, a substance separated during 1. Find the highest common factor between the numbers in fractional distillation. the molecular formula: Fractionating A piece of apparatus used to improve the column (n) separation of solvents during fractional Highest common factor of 4 and 8 is 4. distillation. Distillate (n) A liquid product condensed from its vapour 2. Divide the chemical formula by the highest common fac- during distillation. tor: C = 4/4 = 1 H = 8/4 = 2 • Distillation separates substances by boiling point. Chromatogram The pattern produced when separating a 3. Write down the empirical formula: • Simple distillation separates a solvent from a (n) mixture using chromatography, Stationary phase A substance in the solid or liquid state that CH2 solution. () does not move during chromatography. Mobile phase () A substance in the liquid or gas state that Chromatography Chromatography moves during chromatography. Chromatography separates substances by their Tier 2 vocabulary Definition solubility. Symbol (n) A shorthand way to represent an element on the periodic table . Chromatography is an analytical technique. Separate (v) Cause to move or be apart. Volatile (adj) (of a substance) easily evaporated at nor- mal temperatures. .