2(f) Acids, alkalis and titrations
Pearson Edexcel International GCSE Chemistry · 4CH1
Paper 2 | Whole paper: All content including bold C statements
The pH scale, indicators, neutralisation, and the titration that turns all of it into a number.
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.