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Solids and liquids

Heat melts a solid and turns it into a liquid. Cooling freezes a liquid into a solid.

Different solids melt at different temperatures, some high, some low. These are called their melting points.


Heat can change solids into liquids or gases.

  • Most solids melt into liquid when they are heated.

  • A liquid evaporates into a gas when it is heated.


When we cool something we take heat away from it. Cooling changes a gas into a liquid, and a liquid into a solid.

  • A gas condenses into a liquid when it is cooled.

  • A liquid freezes into a solid when it is cooled.

Heating and cooling an ice lolly

Melting points

Different solids melt at different temperatures. Ice melts at 0 degrees Celcius (0°C). Chocolate melts at about 35°C. We say that chocolate has a higher melting point than ice.

Metals, like aluminium and iron, also melt when we heat them. They have very high melting points. They have to be very hot to melt.

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