Pearson Edexcel International GCSE Chemistry · specification 4CH1 · Paper 2 | Whole paper: All content including bold C statements · Free · no account needed
2(f) Acids, alkalis and titrations (4CH1 specification)
The pH scale, indicators, neutralisation, and the titration that turns all of it into a number.
Learn it on Incandio
The 5 Incandio pages that teach this — each explained in full, then proved in marked questions, taught back to an AI pupil and defended in a debate. Completely free.
- Uses of Metals, and Alloys — Why each metal is used where it is — and why almost none of them is used pure.
- Acids, Alkalis and the pH Scale — Three indicators that answer a yes-or-no question, and one scale that answers 'how much'.
- Hydrogen Ions and Neutralisation — What every acid has in common, what every alkali has in common, and why every neutralisation is one equation.
- Titrations — Finding the exact volume that neutralises — and then making the salt again without the indicator in it.
- Solubility Rules and Proton Transfer — Which salts dissolve, and the broader definition of an acid that explains why ammonia counts.
The teaching route this belongs to: Topic 2 · Inorganic chemistry (Chemistry) — the lessons in order, with every gate.
Specification coverage
Topic 2 Inorganic chemistry (f) Acids, alkalis and titrations — statements 2.25–2.34C (includes bold C statements assessed on Paper 2 only)
Assessment objectives: AO1, AO2, AO3. Suggested learning time: 90 minutes.
Required knowledge
- Acids and alkalis in terms of hydrogen and hydroxide ions in aqueous solution
- The pH scale and the colours of common indicators
- Neutralisation and the general reactions of acids with metals, bases, metal oxides and carbonates
- The technique of titration using a burette and pipette
- Bold C statements: strong and weak acids, and titration calculations in greater depth
Required skills
- Describe a titration precisely enough for it to be repeated
- Identify and use concordant results
- Complete a titration calculation from burette readings to concentration
- Describe and evaluate the required practical: Investigate the neutralisation of a dilute acid by an alkali by titration, using an indicator.
How it is examined
- Multiple-choice and short-answer recall
- Application of the content to an unfamiliar context
- Extended open-response, marked on the quality of a connected explanation
- Practical questions on method, variables, data and sources of error
Common mistakes
- Averaging all titres including the rough one. Only concordant results within 0.10 cm³ are averaged.
- Confusing 'strong' with 'concentrated'. Strong describes the degree of dissociation; concentrated describes the amount per volume.
- Reading a burette from the top of the meniscus, or forgetting that burettes read downwards.
This page maps the specification. The pages above teach it, and the Chemistry lessons hold the whole course — completely free.