Types of indicators used in titration
There are several different types of indicators that can be used in titration:
1. Acid-base indicators: These types of indicators change color based on the pH of the solution. They are typically used in acid-base titrations. Examples include phenolphthalein, bromothymol blue, and methyl orange.
2. Redox indicators: These indicators change color based on the oxidation-reduction potential of the solution. They are commonly used in redox titrations. Examples include potassium permanganate, iodine, and ceric ammonium sulfate.
3. Complexometric indicators: These indicators are used in complexometric titrations, where metal ions are titrated with a chelating agent. Examples include Eriochrome Black T and Calmagite.
4. Fluorescent indicators: These indicators emit fluorescence when exposed to specific wavelengths of light. They are used in fluorescent titrations, such as those involving transition metal ions.
5. Adsorption indicators: These indicators are based on the adsorption of a colored species onto a solid support, such as an ion exchange resin. They are commonly used in ion exchange titrations.
6. Indicator electrode: This is an electrode that directly measures the potential of the solution being titrated. It is particularly useful in potentiometric titrations, where the potential change is used to determine the equivalence point.
It's important to note that the choice of indicator depends on the nature of the titration and the analyte being measured. The indicator should have a suitable color change at the equivalence point of the titration.