Study Notes
Specific heat capacity and latent heat are key concepts in thermodynamics, focusing on energy changes in substances.
- Specific Heat Capacity — the energy required to raise the temperature of 1 kg of a substance by 1 °C or 1 K. Example: Water has a high specific heat capacity, meaning it heats up and cools down slowly.
- Latent Heat — the energy required to change the state of 1 kg of a substance without changing its temperature. Example: The latent heat of fusion for water is 330 kJ kg⁻¹, which is the energy needed to melt ice into water.
- Specific Latent Heat of Fusion — energy required to convert 1 kg of solid to liquid without temperature change. Example: Melting ice into water.
- Specific Latent Heat of Vaporisation — energy needed to convert 1 kg of liquid to gas without temperature change. Example: Boiling water into steam.
Exam Tips
Key Definitions to Remember
- Specific heat capacity is the energy needed to raise the temperature of 1 kg of a substance by 1 °C or 1 K.
- Latent heat is the energy required to change the state of 1 kg of a substance without changing its temperature.
Common Confusions
- Confusing specific heat capacity with latent heat, as they involve different processes.
- Forgetting that latent heat involves no temperature change during state transitions.
Typical Exam Questions
- What is specific heat capacity? It is the energy required to raise the temperature of 1 kg of a substance by 1 °C or 1 K.
- How do you calculate the energy needed for a temperature change? Use the formula ΔQ = mcΔθ.
- What is the difference between latent heat of fusion and vaporisation? Fusion is for solid to liquid, vaporisation is for liquid to gas.
What Examiners Usually Test
- Understanding of the definitions and units of specific heat capacity and latent heat.
- Ability to perform calculations involving ΔQ = mcΔθ and Q = Lm.
- Knowledge of practical applications and implications of specific heat capacity and latent heat in real-world scenarios.