AQA A Level Chemistry Required Practicals

Measuring the Molar Volume of a Gas

Measuring the molar volume of a gas: collecting CO₂ over water, the graph of volume against mass, the calculation to 24 dm³ mol⁻¹, percentage uncertainty and the errors examiners ask about.

Required Practical 2: Measurement of an Enthalpy Change

Required Practical 2: enthalpy change via Hess’s law from K₂CO₃ and KHCO₃ with HCl, with q = mcΔT, the Hess cycle, percentage uncertainty and error analysis.

Required Practical 1: Acid–Base Titration

Required Practical 1: finding the concentration of hydrochloric acid by titration with standardised sodium hydroxide, with method reasons, concordant titres, the worked calculation, error directions and percentage uncertainty.

Required Practical 1: Making a Volumetric Solution

Required Practical 1: preparing a standard solution of sulfamic acid and using it to find the concentration of sodium hydroxide by titration, with method, sample data, calculation, uncertainty and common errors.

Comparing the Rates of Hydrolysis of Halogenoalkanes

Practical Skills: Rates of Hydrolysis: comparing the rates of hydrolysis of halogenoalkanes with aqueous silver nitrate in ethanol at 50 °C, the role of each reagent, silver halide colours, 1/t, bond enthalpies and carbocation stability, with errors, improvements and exam points.

Preparing an Organic Liquid: Chlorination of 2-methylpropan-2-ol

The chlorination of 2-methylpropan-2-ol (Practical Skills: Organic Preparation): Sₙ1 mechanism via the tertiary carbocation, separating funnel technique, hydrogencarbonate wash, drying, simple distillation at 50–52 °C, silver nitrate test with nitric acid, worked percentage yield and evaluation.

Required Practical 5: Distillation of a Product (Oxidation of Ethanol)

Required Practical 5: oxidation of ethanol to ethanal by distillation and to ethanoic acid by reflux, with apparatus, boiling points, equations, product tests and exam points.

Required Practicals 4 and 6: Identifying Ions and Functional Groups

Required Practicals 4 and 6: identifying unknown organic liquids and inorganic solids by test-tube reactions, with the method, safety, ionic equations with state symbols, the evidence trail, exam data practice and interactive checks.

Required Practical 3: Effect of Temperature on the Rate of Reaction

Measuring rates of reaction: sodium thiosulfate and acid, rate ∝ 1/t, the effect of temperature and concentration, gas syringe and mass loss methods, tangents and errors.

Gravimetric Analysis: Water of Crystallisation and Thermal Decomposition

Gravimetric analysis: water of crystallisation by heating to constant mass, crucible technique, thermal decomposition of carbonates, composition calculations and errors.

Required Practical 7: Rate by Continuous Monitoring and Initial Rates

Following reaction rates: the iodination of propanone by titration (zero order in iodine), the iodine clock reaction, initial rates from 1/t, rate equations, mechanism, errors and uncertainty.

Finding the Activation Energy of a Reaction: the Arrhenius Plot

Finding the activation energy of a reaction: a clock reaction at five temperatures, the Arrhenius plot of ln(1/t) against 1/T, gradient = (−Eₐ) / (R), the worked calculation, errors and improvements.

Required Practical 9: pH Curves and the Ka of a Weak Acid

Finding the Ka of a weak acid: pH meter calibration, Ka from pH, half-neutralisation and pH = pKa, the weak acid pH curve, indicators, buffer action and errors.

Required Practical 8: Measuring the EMF of an Electrochemical Cell

Measuring cell potentials: half-cells, salt bridge, high-resistance voltmeter, E⦵cell = +1.10 V for zinc–copper, concentration effects, the standard hydrogen electrode, feasibility, errors and uncertainty.

Redox Titrations: Manganate(VII) and Iodine–Thiosulfate

Redox titrations: iron(II) with potassium manganate(VII), iodine with sodium thiosulfate, mole ratios from half-equations, worked calculations, uncertainty and errors.

Preparing a Transition Metal Complex

Preparing a transition metal complex: tetraamminediaquacopper(II) sulfate from copper(II) sulfate and ammonia, ligand substitution, colours, ethanol crystallisation, filtration, washing, drying and percentage yield.

Required Practical 11: Identifying Transition Metal Ions in Solution

Identifying transition metal ions with sodium hydroxide and ammonia, the second-year organic functional group tests, and worked inorganic and organic unknowns with their equations.

Required Practical 10: Preparing a Pure Organic Solid (Aspirin) and Testing Its Purity

The preparation of aspirin: 2-hydroxybenzoic acid with ethanoic anhydride, recrystallisation, filtration under reduced pressure, percentage yield, the melting point, TLC and the iron(III) chloride test as tests of purity, and the common errors.

Required Practical 12: Separation by Thin-Layer Chromatography

Thin-layer chromatography: the method with reasons, adsorption against solubility, calculating and comparing Rf values with standards, visualising spots, checking purity and evaluating errors.