Formulations: A formulation is a mixture that has been designed as a useful product. Many products are complex mixtures in which each chemical has a particular purpose. Formulations are made by mixing the components in carefully measured quantities to ensure that the product has the required properties. Formulations include fuels, cleaning agents, paints, medicines, alloys, fertilisers and foods.

The idea

A formulation is a mixture deliberately designed as a useful product, so its components are chosen and combined for a purpose rather than occurring together by chance. Each chemical in the mixture has a particular job: in a paint, a pigment gives colour, a solvent keeps it fluid and a binder helps it stick. Because the product must behave consistently, the components are mixed in carefully measured quantities, so the proportions are controlled to give the required properties. Fuels, cleaning agents, paints, medicines, alloys, fertilisers and foods are all examples. Unlike a pure substance, a formulation can be separated by physical means and its composition can be adjusted.

What earns the marks

• States that a formulation is a mixture designed and made as a useful product, not a naturally occurring mixture.
• Explains that each component has a particular purpose or function within the product.
• Describes that components are mixed in carefully measured quantities so the product has the required properties.
• Gives a valid example such as fuel, cleaning agent, paint, medicine, alloy, fertiliser or food and links it to its purpose.
• Distinguishes a formulation from a pure substance by noting it contains two or more components that can be present in controlled proportions.
• Uses the idea of required properties to explain why the exact amounts of each component matter.

Common mistakes and how to put them right

• Treating any mixture as a formulation.

  Put it right: A formulation is deliberately designed and measured, so sea water or muddy water is a mixture but not a formulation.

• Assuming a formulation must contain only one chemical.

  Put it right: Formulations are complex mixtures, often with several components each doing a different job.

• Thinking the quantities can be approximate.

  Put it right: Components are measured carefully because the proportions control the product's properties.

• Confusing a formulation with a compound.

  Put it right: The components in a formulation are not chemically bonded together and can be separated by physical means.

Exam tips

• When asked to identify a formulation, name the product and state at least two components with their purposes.
• Use the phrase carefully measured quantities when explaining why a formulation works, as this shows understanding of controlled composition.
• If given data about a product, compare the stated components with the definition rather than judging by appearance alone.
• Link each example to a required property, such as a fuel burning steadily or a medicine delivering the correct dose.