Classic Baking Soda and Vinegar Volcano

The vinegar-and-baking-soda volcano is a rite of passage for science students everywhere. The reaction between acetic acid (vinegar) and sodium bicarbonate (baking soda) produces carbon dioxide gas, which forces the soapy mixture out of the cone in a satisfying foam eruption. Red food colouring makes it look like lava.

What You’ll Need

• Cardboard or an empty plastic bottle (500 ml) for the inner core
• Newspaper strips and flour-water paste (for papier-mâché)
• Brown and red paint
• Baking soda (sodium bicarbonate) — 2–3 tablespoons
• White vinegar — 100 ml
• A few drops of red food colouring
• 1 tsp dish soap
• Tray or large plate to catch overflow

Step-by-Step Instructions

1. Build the core: Stand a plastic bottle in the centre of a cardboard base. Scrunch newspaper around it to form a cone shape, taping it in place.
2. Apply papier-mâché: Dip newspaper strips into flour-water paste (1:1 ratio) and layer them over the newspaper cone. Apply 3–4 layers, leaving the bottle mouth exposed at the top. Allow to dry fully (overnight is best).
3. Paint the volcano: Paint the outside brown with streaks of dark grey for rock texture. Add streaks of red and orange near the top for a lava effect. Let dry.
4. Prime the reaction: Place the volcano on a tray. Pour the baking soda into the bottle (use a funnel). Add the dish soap and a few drops of red food colouring.
5. Erupt! Pour the vinegar into the bottle and step back — the eruption begins in seconds.
6. Repeat: Add more baking soda and vinegar for multiple eruptions in the same session.

Safety Notes

• Vinegar is mildly acidic — avoid getting it in eyes. Rinse with water if contact occurs.
• Conduct the experiment on a tray or outdoors as the foam can overflow significantly.
• Food colouring can stain surfaces and clothing — protect the work area.

Tips & Troubleshooting

• Adding more dish soap produces a foamier, more dramatic eruption.
• Warm vinegar reacts faster than cold.
• For a science fair, present the chemical equation: NaHCO₃ + CH₃COOH → CO₂ + H₂O + CH₃COONa