KS2 Science: How much gas is there in a bottle of fizzy drink?

Primary resources > KS2 Science > Experiments in controlled environments

Video summary

In this short film presenters Harry and Cayana devise an investigation for measuring how much gas is in a bottle of fizzy drink.

They attach a rubber bung with a rubber hose onto the bottle.

Then bubble off the fizz through cylinders of water.

They realise there is far more gas in there than they predicted!

This short film is from the BBC Teach series experiments in controlled environments.

Teacher Notes

Before Watching

Show your learners a 500ml bottle of fizzy drink. Ask them which states of matter they can identify in the materials that make up the bottle of fizzy drink? They may notice the solid bottle, the liquid drink and the gas both within the drink and at the top of the bottle.

Now ask them to predict how much gas they think is in the bottle in millilitres. Encourage them to explain reasons for their prediction.

After Watching

Try the investigation out for yourself. Do your learners gather similar results? They could develop this enquiry into a comparative test by comparing different bottles of fizz. Are some types of fizzy drink more fizzy than others?

You could try weighing a can of fizzy drink, then leaving it open so that the drink goes flat. Does its weight change? What causes it to get lighter? What does this tell you about the gas inside? Through these investigations your learners will see that gases have mass.

Ideas for further learning

Research the affect that carbonated drinks have on your teeth. Why aren’t fizzy drinks good for you? Find out more about carbon dioxide. Why is it used to help put out fires?

Key Scientific Ideas

• Carbon Dioxide - fizzy drinks contain a gas called carbon dioxide, a colourless odourless gas that dissolves in water under pressure. Carbon dioxide is necessary for life on Earth. When animals breathe out, they release carbon dioxide into the air. Plants use this carbon dioxide to make their own food through photosynthesis. Plants then release oxygen into the air for animals to breathe in. Carbon dioxide makes up about 0.03% of Earth’s atmosphere.

• Gas – gas particles move about at high speeds; they have no fixed shape or volume. Gas will spread to fill any space that is available. This means that in contrast to liquids and solids, the volume of a gas is not fixed. If gas is pressurised, its volume contracts. If you decrease its pressure, its volume increases. The gas in the bottle of fizz was under a lot of pressure, its volume was small. However, when the bottle was opened the gas pushes the water out of the cylinder, we can see that under less pressure, the volume of the gas is much larger.

Developing practical enquiry skills

• Observation Over Time – in this type of enquiry we simply make observations or measurements over a period of time. These observations can take place over seconds, minutes, hours, or days, or over longer periods of time, such as weeks or months. In this case our presenters made their observations over a period of about 10 minutes. When learners make observations over time, they should make notes about what they see happening, looking for changes.

• Measuring volume of gas - fill the measuring cylinder with water. Stand it upside down in the water. Connect the bung into the bottle, with a piece of rubber tubing. Record how many cylinders of water are displaced and multiply that by the volume of each cylinder in millilitres. Continue timing until no more carbon dioxide appears to be given off. Each time the presenters change the cylinder, they lose gas. So, they don’t obtain an accurate measurement. However, they are able to ascertain that the amount of gas in the bottle is far more than they predicted.

These short film clips support teachers with practical enquiry. They can be both used as a resource for learners to watch at home. Or as a stimulus to support learners to plan and conduct their own science investigations. They link to the UK Science curricula.

Materials

• Compare and group materials together, according to whether they are solids, liquids or gases.

Science enquiry / Working scientifically skills

• Pupils should plan different types of scientific enquiries to answer questions, including recognising and controlling variables where necessary.
• Pupils should take measurements, using a range of scientific equipment, with increasing accuracy and precision, taking repeat readings when appropriate.
• Pupils should record data using tables.

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