What happens when you pour sour lemon on a pile of white baking powder?
Here is a little dish of white powder… it is called baking soda. And here is a drop of sour lemon, all squeezed and ready. Now the lemon drop is going to fall, right onto the white powder. What do you think will happen? Ready to guess… will it FIZZ with happy bubbles, or just SIT there quietly?
After you watchWhat happens when you pour sour lemon on a pile of white baking powder?
The short answer
Pouring sour lemon juice on baking soda makes it fizz with bubbles. Lemon juice is an acid, and acids make baking soda let go of a hidden gas. That escaping gas is the fizz. Plain water has no sour acid in it, so water just makes the powder wet and there are no bubbles.
Try this next
- What if you try a sour drink that is not lemon, like orange juice? Set up two matching powder piles. Guess first which sour drink fizzes more, then pour them side by side and watch the bubbles race.
- What if you pour on a much bigger pile of powder? Guess whether more powder makes more fizz. Then drip the same little drop of lemon on a giant pile and see if it keeps bubbling or stops with powder left over.
The whole story
How it works
Baking soda is a white powder that holds a hidden gas inside it. Sour things like lemon juice and vinegar are acids. When the sour lemon touches the baking soda, it sets that hidden gas free, and the gas rushes out as lots of little bubbles you can see and hear — that is the fizz. Plain water is not sour, so it cannot set the gas free, and the powder just gets soggy.
What people get wrong
Kids often think anything wet will make the powder bubble, since the lemon is wet. But being wet is not what makes the fizz — only sour things do. Pour plain water on baking soda and you get no bubbles at all, just a wet pile. The fizz only comes when something sour, like lemon, touches it.
The catch
The fizz is fun and useful — that same bubbling gas makes cakes puff up and makes bath bombs hiss in the tub. But once all the bubbles have escaped, the fizzing stops and that powder is all used up. Plain water leaves the powder calm and ready for later, but you will never get a single bubble from water alone.
Questions kids ask
Why does lemon make baking soda fizz?
Lemon juice is sour — it is an acid — and acids make baking soda let go of a hidden gas. That gas rushes out as bubbles, and the bubbles are the fizz.
Why does plain water not make it fizz?
Plain water is not sour, so it cannot set the hidden gas free. The powder just gets wet and soggy, with no bubbles at all.
Does vinegar work like lemon?
Yes! Vinegar is sour too, so it also makes baking soda fizz. That is why the vinegar-and-baking-soda volcano bubbles over.
Talk about it
- We see bubbles in fizzy pop and in this fizz — what do you think those bubbles are made of?
- Plain water made the powder wet but not bubbly. What do you think the lemon has that the water is missing?
- Where else have you seen something fizz the moment it got wet, like a bath bomb in the tub?
Keep going
What else makes you wonder?
- If the fizz is a gas coming out, where was all that gas hiding before the lemon touched it?
- Orange juice and vinegar are sour too — do you think they would make the powder fizz like the lemon did?
- When the bubbles all stop, what is left in the dish — and could you make that same pile fizz again?