Acids, bases and salts

Indicators

An indicator is a chemical that changes colour in acidic, alkaline and neutral solutions. Some common indicators include red litmus paper and blue litmus paper.

IndicatorAcidicNeutralAlkaline
Red litmus paperredredblue
Blue litmus paperredblueblue
Blue litmus paper is dipped in a beaker of acid and turns red.
Blue litmus paper changes to red in acids
Red litmus paper changes to blue in alkalis.
Red litmus paper changes to blue in alkalis