Litmus Indicator

Learning objective1. Examples of acids and alkalis2. Describe how to use litmus

indicator3. Identify acids and alkalis using

litmus indicator

What do all these things have in common?

How can you test a liquid to find if it is an acid or an alkali?

An indicator is a special chemical that changes to a different colour in an acid or an alkali.

What is an indicator?

Litmus paper and litmus solution are examples of indicators.

Red Litmus is red in acid. Blue litmus turns red in acid

Blue Litmus is blue in alkali. Red litmus turn blue in alkali

Litmus test experiment

The Litmus TestAim:

Use Litmus Paper to identify different acid, alkali and neutral solutions.

Wear goggles!

Method:• Collect your equipment.• In 9 wells of a spotting tile add one piece of red litmus paper.• To each well add 2 drops of each substance following the grid below.

• kettle descaler• tap water• battery acid• oven cleaner• kitchen surface cleaner• ammonia• shower cleaner• bleach• Vinegar

• Record the colour that the red litmus paper has changed to in your results table.

• Using a paper towel put the litmus paper in the bin. Rinse and dry the spotting tile.

• Repeat steps above using blue litmus paper.• Identify the solution as acid, alkali or neutral.

Kettle descaler Tap water Battery Acid

Oven cleanerKitchen surface cleaner

Ammonia

Shower cleaner Bleach Vinegar

Household cleaners Red litmus Blue Litmus Acid or

alkali?Kettle

DescalerOven cleaner

Shower cleaner

Tap waterKitchen surface cleanerBleach

Battery Acid

Ammonia

Vinegar

Household cleaners Red litmus Blue Litmus Acid or

alkali?Kettle

Descaler Acid

Oven cleaner AlkaliShower cleaner Acid

Tap water NeutralKitchen surface cleaner

Neutral

Bleach Alkali

Battery Acid Acid

Ammonia

Vinegar Acid