Science Experiments

Freezing lemonade bottles

Sun, 18th Mar 2007

Listen Now    Download as mp3 from the show Cambridge Science Festival Q&A

What you Need

A small bottle of unopened fizzy drink (carbonated). It is a good idea to remove the label.

A large bowl of ice - you can bury the bottle in

Water

Salt - several tablespoons

If you have one

A thermometer

What to do

1- Add some water to the ice so it is about half covered in water

2- Add the salt to the ice (if you have a thermometer this should bring the temperature down to about -4C

3- Bury the fizzy drink bottle in the ice

4- Wait 20-30mins - if the drink freezes you have waited too long.

5- Open the bottle, watch what happens

What may happen

The bottle should turn to slush in a few seconds in front of your eyes.

Why does it happen?

Before you open the bottle of lemonade or beer there is lots of carbon-dioxide (CO2) dissolved in the lemonade. If you dissolve carbon-dioxide in water it reduces the freezing point (in the same way that salt does. So you can cool the lemonade down to -2 or -3C without it freezing.

However when you open the bottle you release the dissolved carbon-dioxide increasing the freezing point and creating lots of little bubbles.

A closed Lemonade Bottle

An opened Lemonade Bottle

Freezing point

-3C

Freezing point

-0.5C

    The lemonade is now below its freezing point, and there are lots of bubbles for the ice crystals to start on, so it freezes in front of your eyes!

Dave Ansell

Multimedia

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