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Description

Do some baking soda science to make edible treats such as hokey pokey, and explain the science behind it.

Choose one or do them all!

Resources

Hokey Pokey
Ingredients, baking paper, saucepan, wooden spoon, measuring spoons, tin, stove.

Fizzy Sherbet
Ingredients, bowls, measuring spoons

Fizzing Lemonade
Ingredients, bowl/jar for mixing, measuring spoons, spoon for mixing, cups for drinking

Instructions

Hokey Pokey (Edmonds recipe)
5 tablespoons sugar, 2 tablespoons golden syrup, 1 teaspoon baking soda
Put sugar and golden syrup in saucepan. Heat gently, stirring constantly until sugar dissolves.
Increase heat and bring to the boil. Boil for 2 minutes. Stir occasionally, if necessary to avoid burning.
Remove from heat. Add baking soda. Stir quickly until the mixture froths up.
Pour into tin lined with baking paper immediately.
Leave until cold and hard. Break into pieces.

Fizzy Sherbet
1 tsp baking soda (sodium bicarbonate), 1 tsp citric acid, 3 Tbsp icing sugar, 2 Tbsp flavoured jelly crystals
Mix ingredients together in a bowl.
Taste to feel the chemical reaction.

The ‘fizzing sensation’ of sherbet is formed by an acid-base chemical reaction between citric acid and baking soda (which is a base), in the presence of a liquid (which in this case, is your saliva), causing tiny bubbles of carbon dioxide (CO2) that tickle your tongue.

Fizzing Lemonade
Lemons, sugar, baking soda, water, bowl/jar for mixing, measuring spoons, spoon for mixing
Squeeze (and strain) the juice of one lemon into a glass
Add 1 teaspoon of bicarbonate of soda (we added it by the 1/2 teaspoon to see multiple reactions)
Give it a stir to really get the reaction happening!
Add some sugar to water to taste and add to lemon mixture. (There should be more frothing but not as big as the first reaction. Why do you think that is?)
Taste your lemonade! (What can you notice? What can you feel on your tongue?)

What's happening?
When the lemon juice (acid) and the bicarbonate of soda (base) mix, they form a chemical reaction known as an acid-base reaction. This is the same sort of reaction that you get when you mix bicarb soda and vinegar, such as in the classic erupting volcano experiment. The reaction produces as gas called carbon dioxide (CO2) which creates bubbles when formed in a liquid like in this fizzing lemonade experiment. This process is called carbonation.
Handy Tips:
- Play around with the quantities. Add more lemon for a greater citrus taste, add more bicarb of soda for greater fizz, add more water to dilute, add more sugar to make it sweeter. What is your perfect combination?

Tags

• Acid base
• Baking soda
• cooking
• science
• STEM
• sweets

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