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Wednesday 19th June 2019

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Reversible and Irreversible Changes

When we make changes to materials sometimes we can change the materials back and sometimes we cannot because it has changed forever.

If we can change the material back it is called a reversible change, if we cannot change the material back it is called an irreversible change.

Look at these examples:

If I cook popcorn kernels in the microwave to make popcorn, I cannot get the popcorn kernels back ever again. This is called an irreversible change.

If I melt some chocolate in the microwave to make liquid chocolate, I could cool the chocolate in a mould to make a solid bar of chocolate again. This is called a reversible change.

Can you decide whether the changes to these materials are reversible or irreversible changes?

1) Freezing water to make ice?


3) Burning charcoal bricks on a BBQ?


5) Frying an egg?


7) Burning gas on the cooker?


2) Baking dough to make bread?


4) Melting butter?


6) Melting ice-cream?

8) Melting ice cubes to make water?


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