Question

"What kinds of error can be introduced by using an indicator that changes from one color to another as opposed to one like phenolphthalein, which changes from clear to pink?

Answer 1

Some indicators are there that are already having some colour and changes colour during titration equivalence point. They create confusion in taking end point reading. For example, the colour of methyl orange is red in acidic medium and changes to yellow in basic medium. Now, if a student is using it in acid-base titration then, its colour transition will take place. From red it will turn to deep yellow then moderate yellow and finally the pale yellow with successive addition of base. Now the confusion arises which yellow should be taken as end point. Titration is all about volume of burette. Even a single additional drop can alter results. Thus, it is always better to employ such indicators that shows a drastic change in colour at equivalence point so that the error can be minimised.