A technician is producing a batch of sunscreen. She describes the sunscreen as a formulation. Explain what is meant by the term formulation and describe one feature that makes the sunscreen a formulation rather than a pure substance.
Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).
Sunscreen contains several ingredients, including UV filters, moisturisers and preservatives, each present in carefully measured quantities.
Model answer (4 marks)
A formulation is a mixture that has been designed for a particular use. In this case the sunscreen is a mixture of several pure substances – UV filters, moisturisers, preservatives and other ingredients – each added in a precisely measured amount. Because the product contains more than one substance, it is a mixture and therefore a formulation, not a pure substance. A pure substance would consist of only one element or one compound, which is not the case for the sunscreen.
Examiner tips
- Define formulation as a mixture for a specific use; mention precise quantities of pure substances; state that more than one ingredient means it is not a pure substance; keep answer concise and use exam‑style terminology.
Common mistakes
- Confusing formulation with a single ingredient; forgetting to mention the precise measurement of each component; describing the sunscreen as a pure substance instead of a mixture.
Mark scheme (4 marks)
- A formulation is a mixture designed for a particular use
- A formulation is made up of exact / carefully measured quantities of pure substances
- The sunscreen contains more than one substance / compound / ingredient (so it cannot be a pure substance)
- A pure substance contains only one element or compound, whereas the sunscreen contains more than one substance
Key terms in this question
Related
- All Eduqas GCSE Chemistry revision notes →
- How to answer a "Explain" question →
- Decode the mark scheme abbreviations →
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