Solids and liquids

Introduction

Heating and cooling

Heating

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.

Cooling

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.

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.