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Indicators

An is a chemical that changes colour in , and solutions. Some common indicators include red litmus paper, blue litmus paper, phenolphthalein, and methyl orange.

IndicatorAcidicNeutralAlkaline
Red litmus paperredredblue
Blue litmus paperredblueblue
IndicatorRed litmus paper
Acidicred
Neutralred
Alkalineblue
IndicatorBlue litmus paper
Acidicred
Neutralblue
Alkalineblue
Blue litmus paper is dipped in a beaker of acid and turns red.
Image caption,
Blue litmus paper changes to red in acids
Red litmus paper changes to blue in alkalis.
Image caption,
Red litmus paper changes to blue in alkalis