The Indicators and how do they work


These are the substances that change their properties , colour or smell when react with an acid or base.


These indicators change their smell when they  react with an acid or a base.  For example :- clove oil, vanilla essence and the smell of onion juice.

The cloth dipped with onion juice looses its smell on treating with base.


The indicators are of following types

  • Natural indicators
  • Synthetic indicators

Natural indicators:- these are obtained from the nature and are used directly without any laboratory treatment. For example;- turmeric and litmus.

Synthetic indicators:- These are the indicators that are synthesised in the laboratory. For example Phenolphthalein and Methyl orange.

Here are some of the observations in the tabular form:-

Name of indicatorTurmeric (yellow)Litmus (purple)Phenolphthalein (colourless)
Colour in acidNo changeRedClourless
Colour in baseRedBluePink

Published by ankushmaster

I am M.Sc (chemistry ) from punjabi university. I am a science teacher with expertise in chemistry, with 8 years of experiance in teaching. i am getting a handsome salary , now i wish to help out the people who need me UNCONDITIONALLY. and I am constantly working on creating a new and easy way of learning the tough things in an effective way. I am constantly working to make authentic and reliable information to be shared with my students and widen the horizons of knowledge.

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