You will need:

• Bakers yeast (1 packet)
• Cup of hot (not boiling) water
• Sugar (2 tablespoons)
• Small plastic bottle

What to do:

1. Stretch out the balloon by blowing it up and then releasing the air. Set the balloon aside for now.
2. Add 2 tablespoons of sugar to the cup of warm water and stir until the sugar dissolves. Add one tablespoon of yeast to the cup and sti briefly.
3. Carefully pour the contents of the cup into the plastic bottle. You may want to use a funnel to prevent spills.
4. Stretch the balloon over the opening of the bottle.
5. Watch the balloon closely. Be patient - it may take a few minutes before you see any changes.
6. If nothing happens, add some more yeast.

How does it work?

Yeast is a type of single celled fungus this is used in baking to make bread rise. Yeast does this by feeding on the sugars in the flour and releasing carbon dioxide gas as waste. The process of breaking down sugar molecules into alcohol and carbon dioxide is called fermentation.

This same process occured inside the bottle. The yeast began to feed on the sugar in the water, releasing carbon dioxide gas. The carbon dioxide gas caused the balloon to fill up.

Ever wondered why there are little holes in your bread? The carbon dioxide from the yeast makes thousands of bubbles in the dough. These air bubbles are what give the loaf of bread its fluffy texture.

Try the same experiement using hotter and colder water. Does the temperature of the water affect how long it takes for the balloon to inflate? What if you substituted juice or soda for the sugar/water solution? Would you get the same result? Try it and find out!

Don't forget to take some pictures of your lava lamps and send them into us to be in with a chance of winning some great prizes.

The School of Chemistry at NUI Galway advise that adult supervision is needed for all experiments. The portions of materials used in the experiments should not be increased from that described and mixtures prepared should not be ingested. The full text should be read before starting any experiment.

• Disclaimer
• Privacy
• Copyright
• Accessibility