When phenolphthalein is used as the indicator in a titration of an HCl solution with a solution of NaOH, the indicator undergoes a colour change from colourless to poink at the end point of the tiration. This colour change occurs abruptly because

When phenolphthalein is used as the indicator in a titration of an HCl

1.	When phenolphthalein is used as the indicator in a titration of an HCl solution with a solution of NaOH, the indicator undergoes a colour change from colourless to poink at the end point of the tiration. This colour change occurs abruptly because
Answer» Phenolphthalein is a very strong acid that is capable of rapid dissociation the solution being titrated UNDERGOES a large the solution being titrated undergoes a large pH change NEAR the end POINT of the tiration phenolphthaein undergoes an irreversible reaction in basic solution Solution :Phenolphathalein being acidic indicator donot undergo dissciation in `HCl`, so remains COLOURLESS but in `NaOH` it undergoes complete dissociation and changes to PINK.