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PH Indicator

Key Stage 3

Meaning

A pH Indicator is a dye which changes colour depending on the pH of its environment.

About pH Indicators

The colour of a pH indicator can be used to tell the pH of a solution.
Different indicators will have a different range of colours for different pH values.
A good pH indicator can be added to solution without affecting the pH of the solution. If a pH indicator changed the pH of a solution it could not give an accurate reading.

Some pH indicators you should know:

Examples

These are the colour ranges of different pH indicator plants.
NaturalIndicators.png

Key Stage 4

Meaning

A pH indicator is a dye which changes colour depending on the concentration of H+ or OH- ions in solution.

About pH Indicators

pH indicators are used to determine the pH of a solution.
Different pH indicators have a different range of effectiveness. Some only have two colours and change between them at a very specific pH. Others can have many different colours over a range of pH values.
These are the colour ranges of some common pH indicators.
PHIndicators.png

References

AQA

Indicators (of pH), page 289, GCSE Combined Science Trilogy; Biology, CGP, AQA
Indicators (of pH), page 369, GCSE Biology, CGP, AQA
Indicators, page 126, GCSE Biology; The Revision Guide, CGP, AQA
Indicators, page 52, GCSE Physics; Third Edition, Oxford University Press, AQA
Indicators, pages 124, 125, 237, GCSE Combined Science Trilogy; Chemistry, CGP, AQA
Indicators, pages 128, 134, GCSE Combined Science; The Revision Guide, CGP, AQA
Indicators, pages 146, 147, 149, 150, 315, GCSE Chemistry, CGP, AQA


Edexcel

pH indicators, page 317, GCSE Biology, CGP, Edexcel