Define about the term Indicators?

The easiest way to determine when the reaction is complete is by using indicators. An indicator is a compound that has a physical property (usually colour) that changes abruptly at equivalence point. Some examples of indicators used for quantitative analysis include eriochrome black T in calcium estimation, methylene blue in sugar estimation, 2,6 Dichlorophenolindophenol in ascorbic acid estimation etc. The usefulness of an indicator lies in the fact that one (or both) of the form of the indicator are intensely coloured.

The appearance, disappearance, or change of indicator colour in a solution during a titration near the equivalence point makes it a useful part of the titration. This change is either because of the sudden disappearance of analyte or appearance of titrant at the equivalence point. What is the equivalence point. Go ahead read on you will soon find out the meaning of this term and other such terms used in the study of volumetric analysis. But first get to know the types of indicators which can be used.