A2 Testing for Acids and Alkalis

Recall the colours produced by the following indicators in acidic solution and alkaline solution: litmus, phenolphthalein, methyl orange and universal indicator.

Blue Litmus Paper: Blue

•          In an Alkali: No change
•          In an Acid: Turns Red

Red Litmus Paper: Red

•          In an Alkali: Blue
•          In an Acid: No change

Universal indicator: Green solution (Yellow Paper)

•          In an Alkali: Green to Purple
•          In an Acid: Red to Green
•          In a Neutral solution: Green

Phenolphthalein: Colourless

•          In an Alkali: Violet
•          In an Acid: Colourless

Methyl Orange: Orange

•          In an Alkali: Orange
•          In an Acid: Pink/Red