A pharmacist describes a painkiller tablet as a formulation. Explain what is meant by the term formulation and give two reasons why it is important that the components of a medicine are mixed in carefully measured quantities.

WJEC GCSE Chemistry (Wales) — 1.5 Rate of chemical change · Explain · 4 marks · View as Markdown

Written & reviewed by James Millett — Biology (Imperial College London), PGCE Science (University of Cambridge).

Model answer (4 marks)

A formulation is a mixture designed for a particular use, made up of exact quantities of pure substances.

1. Each component has a specific purpose – e.g. the active ingredient provides the therapeutic effect, excipients aid manufacturing and stability.

2. Precise quantities are needed so the medicine has the required properties: the correct dose, stability, taste and appearance.

3. If a component is too much or too little the medicine can become unsafe, ineffective or harmful to the patient.

Examiner tips

  • Use the definition of formulation first, then give two clear reasons – purpose of components and safety/effectiveness.
  • Show the link between measured quantities and correct dose, stability and patient safety.

Common mistakes

  • Confusing formulation with a single ingredient; not mentioning the role of excipients.
  • Failing to explain why accurate measurement matters for safety and efficacy.

Mark scheme (4 marks)

  1. A formulation is a mixture designed for a particular use / made up of exact quantities of pure substances
  2. Each chemical/component in the formulation has a particular purpose
  3. To ensure the product has the required/correct properties
  4. Too much or too little of a component could make the medicine unsafe / ineffective / harmful to the patient

Key terms in this question

formulation · components

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