Study Notes
Internal energy is the total energy stored within a system due to the motion and positions of its particles. Energy transfers occur when energy is moved from one system to another, often involving changes in temperature or state.
- Internal Energy — the total energy stored in a system due to the motion and positions of its particles Example: The internal energy of a gas increases when it is heated.
- Specific Heat Capacity — the energy required to raise the temperature of 1 kg of a substance by 1 °C Example: Water has a specific heat capacity of 4200 J/kg°C.
- Specific Latent Heat — the energy required to change the state of 1 kg of a substance without changing its temperature Example: The specific latent heat of fusion is needed to melt ice into water.
Exam Tips
Key Definitions to Remember
- Internal Energy: Total energy stored in a system due to particle motion and positions
- Specific Heat Capacity: Energy needed to raise 1 kg of a substance by 1 °C
- Specific Latent Heat: Energy needed to change the state of 1 kg of a substance without temperature change
Common Confusions
- Confusing specific heat capacity with specific latent heat
- Thinking that internal energy only involves temperature changes
Typical Exam Questions
- What is specific heat capacity? The energy required to raise the temperature of 1 kg of a substance by 1 °C.
- How does internal energy change when a gas is heated? The internal energy increases as the particles gain kinetic energy.
- What happens to the temperature during a change of state? The temperature remains constant as energy is used to change the state.
What Examiners Usually Test
- Understanding of energy transfers during heating and cooling
- Ability to calculate energy changes using specific heat capacity and specific latent heat