Blowing Balloons Respiration Style

We have talked about respiration before when I show you how bread is made.

This is another very easy experiment that demonstrates respiration in action and is quicker than the bread, if you are short of time.

All you need is

A balloon

A small clear drinks bottle

A packet of dried yeast

Warm water

1 teaspoon of sugar

Blowing Balloon Respiration Style, Science-sparks



1. Blow the balloon up a few times to give it some stretch. This just makes it easier for the experiment to work.

2. Fill the small bottle about 3cm full of warm water.

3. Add the yeast and swirl until dissolved and then add the 1 teaspoon of sugar.

4. Place the Balloon over the open top so that is seals it.

5 Over the next half an hour watch what happen. (Obviously do other stuff and come back, it may be a little boring to actually watch it for half an hour!)

You should find this happens!


Blowing Balloon Respiration Style, Science-sparks

The Science Bit.

Yeast is a living organism. In order for it to survive it needs to make energy. In its dried form the yeast is dormant, but as soon as you provide it with warmth, water and Sugar (it’s food) it ‘wakens’ and becomes active. The sugar (glucose) reacts with the Oxygen in the bottle to make water, energy and Carbon Dioxide. The carbon dioxide is a gas and this is what you see filling the balloon.

The equation for respiration is

Glucose + Oxygen –> Carbon Dioxide + Water + Energy

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