# Baking Soda Volcano Diorama

How a baking soda and vinegar volcano model foams over, and why the soap traps the carbon dioxide gas that drives the eruption\.

By PETE\!

Topic: Physics & Chemistry

[Open the interactive Jig](https://ask.jig.com/j/tr8PV0mLQ6eq)

## Transcript

### 1. A volcano on the kitchen table

This classic science\-fair model looks like a mountain, but its eruption is pure kitchen chemistry\. Follow it from the hidden setup to the foaming overflow and find out what really makes the foam\.

Drag anywhere to turn the diorama and look at it from any side\.

### 2. A bottle hides inside

Cut away a quarter of the clay and the secret appears: a small plastic bottle stands in the middle of the cone\. Its neck opens at the crater, so everything poured in happens inside the bottle\.

The cone is only scenery\. It shapes where the foam flows\.

### 3. Load the reactant

Two to three tablespoons of baking soda go in first, with a squeeze of dish soap and a few drops of red food colouring\. Nothing happens yet: dry baking soda waits for an acid\.

Baking soda is sodium bicarbonate, a mild base\.

### 4. Pour the vinegar

Vinegar is about five percent acetic acid in water\. Pour half a cup into the crater and the acid meets the baking soda at once\. Watch the bottle fill with foam, then overflow\.

### 5. Where the foam comes from

The acid and the base swap partners\. Carbonic acid forms and splits straight away into water and carbon dioxide gas\. The soap traps the gas in millions of bubbles, and the growing foam has only one way out\.

Baking soda \+ vinegar make sodium acetate, water and carbon dioxide\.

### 6. It runs out

The fizzing slows as the baking soda is used up, and the foam settles into a pink puddle\. A fresh load of baking soda and vinegar starts it all again\.

Use about one part baking soda to three parts vinegar\.

### 7. Real volcanoes are different

This foam is cold and harmless\. A real volcano erupts molten rock pushed up by gases dissolved in magma\. The model only shares the idea that expanding gas forces material out through a narrow vent\.

Wear eye protection and work on a tray or outdoors\.