Redox titrations are a type of titration in analytical chemistry in which the equivalence point of the reactants is determined by observing a colour change of a redox indicator. The redox indicator is a compound that changes colour when it is reduced or oxidised.

There are many different types of redox indicators, but some of the most common include:

• Phenolphthalein: This indicator is colourless in acidic solution and turns pink in basic solution. It is often used in titrations involving acids and bases.

• Methyl orange: This indicator is red in acidic solution and turns yellow in basic solution. It is also often used in titrations involving acids and bases.
• Potassium permanganate: This indicator is purple in acidic solution and turns colourless in basic solution. It is often used in titrations involving reducing agents.
• Potassium dichromate: This indicator is orange in acidic solution and turns green in basic solution. It is often used in titrations involving reducing agents.
• Ferrous ammonium sulfate: This indicator is pale green in acidic solution and turns red in basic solution. It is often used in titrations involving oxidising agents.

The choice of redox indicator for a particular titration depends on a number of factors, including the pH of the solution, the concentration of the reactants, and the desired end point.

The end point of a redox titration is the point at which the amount of oxidant added is exactly equal to the amount of reductant present. At this point, the indicator will change colour, signalling the completion of the titration.