The Science of Sweets

The science of sweets is the chemistry behind the treats we love, from fizzy drinks and sherbet to candy floss. Much of it comes down to carbon dioxide, the same gas we breathe out, and how it makes bubbles. Add in acids, sugar and a few colour-changing reactions, and you have hands-on science the whole family can see, hear and sometimes taste.

Fizzy drinks are made by dissolving carbon dioxide gas into the liquid under pressure. While the bottle stays sealed, the gas stays hidden. Open it, and the pressure drops, so the gas escapes as bubbles. Those bubbles need somewhere to start growing. Drop something with a rough surface, like certain mints, into a fizzy drink and millions of tiny bumps give the gas places to form all at once. The result is a giant fizzy fountain.

Sherbet is sugar mixed with bicarbonate of soda and an acid, such as citric acid. While it's dry, nothing happens. When it touches the wet inside of your mouth, the acid and the bicarbonate react and give off carbon dioxide. That's the tingly fizz on your tongue. It's the same kind of reaction as mixing vinegar with bicarbonate of soda, just much tastier.

A candy floss machine has a spinning head in the middle that heats sugar until it melts. As the head spins, the liquid sugar is flung out through tiny holes. The thin threads cool and harden almost instantly in the air, forming fine strands that are wound onto a stick. It looks like a big fluffy cloud, but it's mostly air and sugar.

Some substances change colour depending on whether they're mixed with an acid or an alkali. These are called indicators. Red cabbage juice is a well-known example: it turns pink or red in acids like lemon juice, and green or blue in alkalis. It's the kind of science that looks like magic, which makes fizzing potions all the more fun.

Yes, and it's a treat for grown-ups too. Children get to see real chemistry happening in front of them, with fizz, colour and bubbles that make every idea easy to follow. Asking why things happen is part of the fun, and the answers are often surprising. Just be ready for requests to try it all again at home.

You might also like Explosive Science, Extreme Ice Creams and Glow Monster Slime Lab.

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