You will need

• 1 plate or tray
• 1 lemon
• 1 cutting knife (to cut the lemon)
• 1 butter knife
• Baking soda
• 1 table spoon
• Food colouring (1 to 4 colours of your choice)

What to do

1. Cut your lemon in half. Then cut of a bit at the bottom, so that the lemon can now stand up.
2. Place the lemon on the plate or tray with the wide side facing up.
3. Use the butter knife to poke holes in the flesh.
4. Add 8 to 10 drops of food colouring spread out over the lemon.
5. Add 1 heaped table spoon of baking soda.
6. Poke with the butter knife to mix the baking soda with the lemon juice.

The acid in the lemon reacts with the baking soda to form salt, water and carbon dioxide gas. The carbon dioxide gas will cause fizzing. We also call this effervescence.

You can watch this experiment on YouTube: