1. Water can be a solid (ice), a liquid or a
gas (water vapour).
2. Melting occurs when a solid substance
changes into a liquid state.
3. The melting point is the temperature at
which the solid becomes a liquid.
4. Different substances have different
melting points, e.g.: Iron melts at 1538°C
and ice melts at around 0°C.
5. If you heat a liquid, it will eventually
boil. We call this the boiling point.
6. Different substances boil at different
temperatures e.g.: Iron boils at 2862°C
and water at around 100°C.
7. Boiling points and melting points can vary
slightly depending on air pressure or
impurities in the liquid.
An example is that water boils at about
96°C in Johannesburg because of the
lower air pressure.