Melting & Boiling
Physics: AQA GCSE Higher, topic 3.2.7
Changes of State
Objects can change state from one state of matter to another. Melting and boiling are examples of changes of state.
Melting - solid to liquid
- If we heat a solid, the solid particles vibrate more energetically, until they have enough energy to overcome the forces between them.
- This is when the solid melts (becomes a liquid).
- The temperature needed for this to happen is the melting point.
- Melting is sometimes also called fusion.
Boiling - liquid to gas
- If we heat a liquid, the liquid particles move more energetically until they have enough energy to escape completely from the forces between them.
- The particles become a gas and move completely freely.
- The temperature needed for this to happen is the boiling point. Boiling can be called vaporisation.
Condensation - gas to liquid
- When the temperature of a gas decreases to the boiling point, the strength of the forces between particles increases and the particles condense to become a liquid.
- For the same material, its boiling point is the same as its condensing point.
Solidifying (Freezing) - liquid to solid
- When the temperature of a liquid decreases to the melting point, the strength of the forces between particles increases and the liquid solidifies to become a solid.
- For the same material, its melting point is the same as its freezing point.
Test yourself on Melting & Boiling
What is another term for melting point?
When does a liquid boil?
Which of these involves a gas changing state?