Make your own Christmas gifts, with help from a little bit of science!
A chemical reaction that you can eat: honeycomb
All cooking is chemistry in action but my favourite edible experiment is honeycomb or cinder toffee. If you want to get all technical, this reaction is the thermal decomposition of sodium hydrogen carbonate to produce sodium carbonate, water and carbon dioxide gas. Basically, heat up baking soda and it gives off gas! If it is mixed up in some lovely gloopy melted sugar when this happens, you’ll get bubbly toffee which makes a great Christmas present for someone with a sweet tooth.
You will need: 200g caster sugar, 5tbsp golden syrup and 2tsp baking soda. Heat the sugar and syrup in a pan while stirring (this is definitely a grown up job!), when it is all melted and golden, remove from the heat and quickly stir in the baking soda. Watch as the chemical reaction happens and bubbles of carbon dioxide form in the toffee. Quickly pour onto a greased baking tray and wait for it to cool before testing out your tastebuds!
Fizzy bath bombs
These bath bombs don’t actually explode but they will fizz away when you put them in the bath. All the ingredients can be found in your kitchen/bathroom cabinet or can be bought in the supermarket (except citric acid which you can find in a chemist or homebrew section, I picked some up in Wilkos for 75p).
You will need:
Corn flour (2 tablespoons)
Citric acid (2 tablespoons)
Bicarbonate of soda (4 tablespoons)
Oil – coconut or olive are good (1 tablespoon)
Fragranced oil/perfume (check it’s safe on skin)
A few dried flower petals (crushed)
What to do:
Mix the corn flour, citric acid and bicarbonate of soda together in a bowl (and flower petals if using). If you want to use fragrance and/or colouring add a few drops to the oil in a plastic cup. Then add the oil slowly to the dry ingredients, mixing in between. You may need add a bit more oil if it doesn’t form a paste (not too much though). When it’s nicely mixed, shape it into balls and leave them to dry on greaseproof paper. They’ll be fully dry in a couple of days then store them in an airtight tub. Pop the balls into cupcake cases and people will think that you have made lovely, thoughtful gifts, not just had fun with science!
What’s going on?
The bicarbonate of soda and citric acid will form a chemical reaction, making lots of carbon dioxide gas. This gas makes the fizzing and bubbles that you see when the bomb is dropped into water. The chemicals can’t react together when they are dry so the fun only starts in the bath!