Chemistry: should I choose it?

How do the chemical structures of materials explain their properties and reactions?

How are materials quantified and classified?

How can chemical principles be applied to create a more sustainable future?

How do chemicals interact with water?

How are chemicals measured and analysed?

How do quantitative scientific investigations develop our understanding of chemical reactions?

Unit 3 AOS1 — What are the current and future options for supplying energy?

This area of study compares the fuels that power transport, industry and the human body. You cover where fossil fuels come from and how coal, petroleum and natural gas are extracted, refined and combusted, then set them against biofuels — biodiesel, bioethanol and biogas — including how each is produced, whether the feedstock is renewable, and how the carbon released compares. The comparisons are quantitative: energy content per gram or per mole, the balanced combustion equation for complete and incomplete burning, the energy released calculated from a thermochemical equation, and efficiency losses on the way from fuel to useful work. The area closes by treating food as fuel, applying the same energy accounting to carbohydrates, proteins and fats metabolised in the body. Thermochemistry and calorimetry belong in this area: use enthalpy changes, energy profiles, specific heat capacity and calibration factors to compare energy transfers. It also covers redox reactions, the electrochemical series, primary galvanic cells and fuel cells, including half-equations, cell voltage and quantitative applications of Faraday’s laws.

Unit 3 AOS2 — How can the rate and yield of chemical reactions be optimised?

This area explains how the rate and extent of reactions can be controlled to produce useful materials. Collision theory connects reaction rate with concentration, pressure, temperature, surface area and catalysts. For reversible reactions, use equilibrium expressions, the reaction quotient and Le Chatelier’s principle to analyse changes in a chemical system. Electrolysis then links chemical production to electrode materials, electrolytes and redox equations. Study rechargeable cells in their discharge and recharge modes, quantitative applications of Faraday’s laws, and the sustainability of processes such as green hydrogen production.

Unit 4 AOS1 — How are organic compounds categorised and synthesised?

This area of study organises organic chemistry into families. You learn to recognise and name compounds by functional group — alkanes and alkenes, haloalkanes, alcohols, aldehydes, ketones, carboxylic acids, esters and amines — and to explain their physical properties, particularly boiling point and solubility, from the intermolecular forces their structures allow. You then move through reaction types: addition to a carbon-carbon double bond, substitution, oxidation of primary alcohols to aldehydes and on to carboxylic acids, and esterification with its reagents, catalyst and conditions. Reaction pathways link these into multi-step syntheses from a named starting material. The area finishes with biomacromolecules — proteins, carbohydrates and lipids — and the condensation reactions that build them and the hydrolysis reactions that break them down in metabolism.

Unit 4 AOS2 — How are organic compounds analysed and used?

This area of study is about proving what a molecule is. You interpret mass spectra, using the molecular ion peak to establish molar mass and fragmentation patterns to identify pieces of the structure; infrared spectra, matching absorption bands to functional groups using the supplied data table; and both proton and carbon-13 nuclear magnetic resonance, where chemical shift indicates environment, the number of signals counts distinct environments, and integration and splitting patterns reveal how many hydrogens sit on neighbouring carbons. High-performance liquid chromatography is used for separation and quantification, including calibration curves and internal standards. The skill the study design actually asks for is combining these techniques — using each spectrum to narrow the possibilities until only one structure survives. Medicinal chemistry closes the unit, covering extraction, purification and how drug design relates to molecular structure. The laboratory component also includes redox titrations, excess and limiting reactant calculations, qualitative functional-group tests, melting-point analysis and distillation; back titrations are excluded from the specified volumetric analysis.

Unit 4 AOS3 — Scientific investigation: sustainable production of energy and/or materials

This investigation is formally Unit 4 Area of Study 3, but it may be undertaken in Unit 3, Unit 4 or across both. Students design a scientific investigation that generates primary data about the production of energy or chemicals, or the analysis or synthesis of organic compounds. Develop a research question and hypothesis, choose and justify the method, control variables, assess risks and manage waste, then analyse results and uncertainty. Evaluate the evidence and limitations before communicating the investigation in a scientific poster. These skills draw on the chemistry and key science skills developed across Units 3 and 4.