Solids, Liquids... Fizz!
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flagWhat you'll discover
- arrow_forwardRecognise a chemical reaction: new things are made that were not there before
- arrow_forwardName the gas made by baking soda and vinegar: carbon dioxide (CO₂)
- arrow_forwardExplain why the fizzing stops when one ingredient runs out
- arrow_forwardUse the balloon to show that an invisible gas still takes up space
A real chemical reaction
Mixing salt into water is just mixing — you can always get the salt back. But baking soda and vinegar do something much more exciting: they react and turn into brand-new substances that were not there before!
The fizz you see is carbon dioxide gas, called CO₂ for short — the same gas that makes soft drinks bubbly. Once it is made, you cannot un-fizz it back into baking soda and vinegar. That is the sign of a true chemical reaction.
Where do the bubbles come from?
Baking soda is a base and vinegar is a weak acid. When they meet, they swap parts and build three new things: a salt dissolved in the liquid, plain water, and CO₂ gas.
The gas has nowhere to go, so it forms bubbles that race upward and burst into foam at the surface. More ingredients means more gas — and a bigger, foamier eruption!
The one that runs out first wins
A reaction is like making sandwiches: if you have lots of bread but only two slices of cheese, you can only make two sandwiches. The cheese ran out first, so the cheese decides when you stop.
Chemists call the ingredient that runs out first the limiting reactant. In the simulation, try lots of vinegar with a tiny pinch of soda — the fizz stops early because the soda ran out. The leftover vinegar just sits there with no one to react with.
Catching an invisible gas
CO₂ is invisible — so how do we know it is real? Trap it! Stretch a balloon over the bottle and the gas has nowhere to escape. As the reaction fizzes, the balloon swells up, blown up by a gas you cannot even see.
This is a famous and totally safe kitchen experiment. Ask a grown-up to try it with you for real: a bottle, a spoon of baking soda, a splash of vinegar and a balloon. Science magic!