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.
© MMIX