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Have fun with foaming fizz!

31st October 2014

We've taken a look inside 365 Science Activities to show junior scientists how bicarbonate of soda fizzes when it reacts with different liquids. Get ready to be amazed...

1. Hot Water
Carefully pour some just-boiled water into a heatproof bowl. Stir in a heaped teaspoon of bicarbonate of soda. What happens?

2. Cold Water
Pour some cold water into a bowl, then add a heaped teaspoon of bicarbonate of soda. Watch to see if anything happens.

Bicarbonate of soda fizzes gently when it mixes with hot water because the heat starts a change that gives off bubbles of carbon dioxide gas. (This is why baking powder - which contains bicarbonate of soda - is used to make cakes. The oven's heat makes the wet bicarbonate of soda produce carbon dioxide gas, which bubbles up inside the cake mixture and tries to escape, making the mixture rise.) Cold water has no effect.

3. Lemon juice or vinegar

1. Put a glass bowl on top of a tray. Half-fill the bowl with lemon juice or clear vinegar.

2. Sprinkle a heaped teaspoon of bicarbonate of soda over the liquid, then watch what happens next.

Vinegar and lemon juice are acids. When you mix them with bicarbonate of soda, the ingredients change very vigorously. This produces lots of bubbles of carbon dioxide gas, which makes the mixture froth and fizz.

4. Foaming fizz

1. Repeat step 1 of activity 3, then stir a good squeeze of washing-up liquid into the lemon juice or vinegar.

2. Add a few drops of food dye, then sprinkle a heaped teaspoon of bicarbonate of soda over the liquid. What happens?

Adding washing-up liquid makes the mixture foam up more because it traps the bubbles of gas from the reaction. The food dye helps you to see more clearly what is happening.

5. Funky froth

Making the fizz from activity 4 in a few different shaped containers to see how the foam flows differently out of the tops.

6. Fizzing sherbet

Buy a packet of sherbet and dab some on your tongue. Can you feel it fizzing?

Sherbet usually contains a mixture of bicarbonate of soda and citric acid powder. When the sherbet gets wet in your mouth, the ingredients start to change, making bubbles of carbon dioxide gas that you can feel tingling on your tongue.

Try varying the quantities of the ingredients to see how much foam you get.

Don't forget to share...

Why not show off your experiments via the Usborne Books at Home Twitter or Facebook pages? We're excited to see some Usborne scientists hard at work!