Question

to a solution A methyl orange solution is added in a test tube. the solution turns pink. on addition of sodium hydroxide solution slowly, the pink colour of the solution disappears. give reasons for your observation.

on addition of little more solution A to the test tube, the pink colour reappears. what is the nature of solution A?

Answer 1

Methyl Orange is a laboratory indicator having formula C14H14N3NaO3S.

When it is added to acid the colour of the solution changes to pink.So A is an acid.

When base is added neutralisation of acid and base occurs and the colour disappears.

Again when acid will be added the acid strength of the solution will increase and methyl orange will be again pink.

It is used in laboratory in volumetric titration and it is best for acids having strength middle of pH scale.

Hope it helps.

Thanks.
Tripathy