Fami
Baking soda volcano
A red foam eruption made with kitchen stuff.
Materials
- 1Small glass
- 2 tablespoonsBaking soda
- 100 mlVinegaror Lemon juice
- 5 dropsRed food colouringor Watered-down poster paint
- 1 teaspoonDish soap
- 1Dinner plate
- 1Tablespoon
Step by step
- 1
Put the glass on the plate
So the foam won't stain the table
- 2
Add 2 tablespoons of baking soda
Straight into the bottom of the glass
- 3
Add soap and colouring
1 teaspoon of soap and 5 drops of red colouring
- 4
Pour in 100 ml of vinegar
All at once, then move your hand away
Result
Eruption!
Why does it happen?
Vinegar is an acid and baking soda is a base. When they mix they make carbon dioxide: thousands of bubbles that the soap turns into foam.
For parents
The science, so you can answer
An acid (vinegar) and a base (baking soda) react and make a gas: carbon dioxide.
Vinegar contains acetic acid and baking soda is a base. When they meet they turn into other substances: water, a salt (sodium acetate) and lots of carbon dioxide, a gas. The gas needs room and rushes upwards; the soap traps it in bubbles, which is why you get foam rather than just fizzing. It is a real chemical reaction: what you started with is gone, it has become something else.
What they will ask you
«What gas is in the bubbles?»
Carbon dioxide. It is the same gas as in fizzy drinks, and the one we breathe out.
«Why does it stop?»
Because one of the two ingredients runs out. Add more vinegar (or more baking soda) and it fizzes again.
«What is the soap for?»
It traps the gas in tiny bubbles. Without soap, the gas escapes at once and you would only see a quick fizz.
«Are real volcanoes like this?»
They are alike in that gas pushes things out. But a real volcano throws out melted rock (magma) at over 1,000 degrees, pushed by gases from deep inside the Earth.
In real life: Baking powder is baking soda mixed with a powdered acid: when it gets wet and warm it makes bubbles of this same gas, and the cake rises.
Animated step by step
Follow it with your phone on the table: it pauses at the end of each step.