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GCSE Chemistry · key term
A mixture of indicators that produces a range of colours at different pH values, allowing the approximate pH of a solution to be estimated.
Used by AQA and OCR
Specification 4.4.2.4 · Paper 1
A mixture of indicators that produces a range of colours and is used with a colour chart to estimate pH.
Revise: pH Scale and NeutralisationUniversal indicator, also called a wide-range indicator, contains several indicator dyes. It changes through a range of colours at different pH values.
Specification C3.3k · Paper 1 (Foundation), Paper 3 (Higher)
An indicator containing a mixture of dyes that produces a range of colours at different pH values.
Revise: Measuring pHTwo important ways to measure pH are universal indicator and a pH meter. Both respond to the chemical conditions in the solution, but they produce different kinds of evidence.
Paper 1 (Foundation), Paper 2 (Foundation), Paper 3 (Higher), Paper 4 (Higher)
A substance that changes colour to show whether a solution is acidic, neutral or alkaline.
Revise: Identifying Group 1 reactivityAdd universal indicator so that any change in pH can be seen. A drop of detergent may be added to reduce the chance of a metal sticking to the side of a trough.
Do not say that universal indicator gives an exact pH. A pH probe provides a more precise numerical measurement.
Do not claim that universal indicator gives an exact pH. Its colour usually gives an approximate value or range.
Universal indicator gives an approximate pH from a colour chart, whereas a calibrated pH meter provides a numerical measurement.
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