Study Notes
The change of state involves the transformation of matter from one state to another, such as solid to liquid or liquid to gas, without changing the number of molecules or mass.
- Melting — the process where a solid turns into a liquid. Example: Ice turning into water.
- Freezing — the process where a liquid turns into a solid. Example: Water turning into ice.
- Boiling — the process where a liquid turns into a gas at its boiling point. Example: Water boiling to become steam.
- Condensing — the process where a gas turns into a liquid. Example: Steam turning into water droplets.
- Evaporation — the process where a liquid turns into a gas at a temperature below its boiling point. Example: Water evaporating from a puddle.
- Specific Heat Capacity — the energy required to raise the temperature of 1 kg of a material by 1 °C. Example: Water has a specific heat capacity of 4200 J/(kg °C).
Exam Tips
Key Definitions to Remember
- Melting: Solid to liquid
- Freezing: Liquid to solid
- Boiling: Liquid to gas
- Condensing: Gas to liquid
- Evaporation: Liquid to gas below boiling point
- Specific Heat Capacity: Energy to raise temperature of 1 kg by 1 °C
Common Confusions
- Confusing boiling with evaporation
- Thinking mass changes during state change
Typical Exam Questions
- What happens to the temperature during melting? It remains constant.
- How does evaporation differ from boiling? Evaporation occurs at any temperature, boiling occurs at boiling point.
- What is the specific heat capacity of water? 4200 J/(kg °C)
What Examiners Usually Test
- Understanding of energy changes during state changes
- Differences between boiling and evaporation
- Calculations involving specific heat capacity