Formulations: mixtures built to a precise, repeatable recipe
Definition
Formulation
A mixture made to a fixed recipe, where each component is measured out in a set quantity to give the product a useful set of properties.
Definition
Mixture
Two or more substances present together that are not chemically joined, so each keeps its own properties and can be separated by physical means.
- A formulation is a mixture that has been designed to a fixed recipe.
- Each component is added in a carefully measured quantity, chosen so the final product does a particular job well.
- Changing the proportions changes the properties, so the recipe is controlled tightly and kept the same from batch to batch.
- A formulation is still a mixture, so its components are not chemically bonded and could in principle be separated again.
Key Idea
- The word formulation adds one idea to mixture: the amounts are deliberately measured to give useful properties.
- Two products can share the same ingredients yet behave differently because their proportions differ.
Formulations around you: paints, fuels, medicines and cleaning products
- Paints are formulations of a pigment for colour, a binder to stick it to the surface, a solvent to make it flow, and additives to control drying.
- Medicines combine a measured dose of the active drug with fillers, binders and coatings so each tablet is the right strength and dissolves properly.
- Fuels such as petrol are blended from hydrocarbons and additives to burn well in an engine.
- Cleaning products, fertilisers, alloys and processed foods are all formulations mixed to a set recipe.
Example
- A 500 mg paracetamol tablet is a formulation: the 500 mg500\,\text{mg}500mg of drug is the active part, and the rest of the tablet is binder, filler and coating.
- The filler and coating carry no medical effect; they set the tablet size and control how it breaks down.
Telling a formulation from a pure substance: look for a measured mixture doing a job
- A pure substance is a single element or compound; a formulation is a mixture of several components.
- A formulation is defined by its recipe: each part is present in a set, measured amount.
- If a product is a blend of ingredients combined in fixed proportions for a purpose, it is a formulation.
Exam technique
- To score the mark, name the components and say each is present in a measured amount for a reason.
- Do not just call it a mixture: the idea being tested is the controlled, purposeful recipe.
Self review
- What is a formulation?
- How is a formulation different from any ordinary mixture?
- Name the main components of paint and state the job of each.
- Why is a paracetamol tablet described as a formulation rather than a pure substance?
- What must you mention to explain why a product counts as a formulation?
