Indicators in acid - base titration
The reaction between an acid and a base is called neutralization. It is very fast and the equilibrium constant for a neutralization reaction is so large that it nearly proceeds to completion. An acid-base titration is a simple and convenient volumetric method for quantitatively estimating the concentration of one, if that of the other is known. A known volume of the solution of an acid or base is transferred to a titration flask with the help of a pipette. we add indicator and start adding known volumes of the other solution in steps with the help of a burette. The point at which the reaction is observed to be complete is called the end point of the titration and is noted by the change in the colour of the indicator. For accurate estimation it is necessary for it to coincide with the equivalence point corresponding to the stoichiometric amounts of the acid and base in the neutralization reaction. A number of weak organic acids and bases which can change its colour with in...