Questacon > Teachers > Outreach Programs > Science Squad > Science Squad: Science Activities > Balloon blow-out

Questacon Science Squad Activities

Balloon Blowout

Science concept

Carbon dioxide gas is a product of the chemical reaction between bicarbonate of soda and vinegar.

Blow it up

Watch as the balloon blows up all by itself.

Special instructions

Teachers should conduct their own risk assessment of this activity.

Class time required: 15 minutes

Materials

• 2 heaped teaspoons of bicarbonate of soda
• 150 ml vinegar
• Plastic drink bottle (600 ml)
• Balloon
• Funnel

What to do

1. Insert the funnel into the neck of the balloon and spoon in the bicarbonate of soda, shaking it into the round part of the balloon.
2. Use the funnel to pour the vinegar into the plastic bottle.
3. Hold the balloon so none of the bicarbonate of soda falls out and carefully stretch the neck of the balloon over the neck of the plastic bottle.
4. Hold the neck of the balloon firmly on the plastic bottle and shake out the bicarbonate of soda so it falls into the vinegar.

What's going on?

• What happens when the two chemicals touch?
• Why does the balloon inflate?
• When the balloon stops inflating, pinch the neck of the balloon, take it off the bottle and tie it up.

When bicarbonate of soda and vinegar mix, a chemical reaction occurs. One of the products of the reaction is carbon dioxide gas.

When the two chemicals mix in the plastic bottle, they keep making carbon dioxide until one of the chemicals has been used up. As the carbon dioxide gas is made, pressure builds up inside the bottle and the gas fills the balloon.