Rainbow eruptions
Bicarbonate in a tray, vinegar in every colour in droppers: each drop fizzes into a little coloured eruption.
Age : age 2+ with a spoon, age 3+ with droppers
Materials
- Bicarbonate of soda : About half a packet.
- White vinegar : One glass per colour.
- Food colourings : Red, yellow, blue: enough for the whole rainbow.
- A baking dish, ice cube tray or muffin tin
- Droppers, or spoons for little ones
- Small pots or glasses : One per colour.
Steps
Prepare
- Spread a good layer of bicarbonate in the dish, or fill each hole of the ice cube tray.
- Pour vinegar into each pot and add a different colour.
- Mix red and yellow for orange, yellow and blue for green, red and blue for purple.
Fizz it up
- Suck up a little coloured vinegar with the dropper.
- Drip a few drops on the bicarbonate: it fizzes straight away!
- Change colour and fill every hole, or draw a rainbow in the dish.
- Watch the colours mix when two eruptions meet.
Vinegar and bicarbonate react and make a gas, carbon dioxide. Its bubbles make the foam. When there's no bicarbonate left in one spot, the fizzing stops: add more.
For toddlers, swap the droppers for spoons. To practise the finger pinch, use droppers.
If it goes wrong
- No more fizz : Add another layer.
- Colours turn brown : Use a new hole for each colour, or empty and start again.
- Dropper won't suck anything up : Fill the pot at least 2 cm deep.
Safety
- Vinegar stings eyes: no eye-rubbing, and wash hands afterwards.
- Colourings stain: apron and covered table.