Specific latent heat (Edexcel GCSE Physics Combined Science): Revision Notes
📚 Revision Notes
Specific Latent Heat
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When a change of state happens, energy is required. This energy required to change the state of a substance is called latent heat. Specific latent heat is the amount of heat energy required to change the state of 1 kilogram of a substance without changing its temperature.
This is different for different materials for changing between different states.
- For cooling, specific latent heat is the energy released by a change in state.
- For melting/freezing between a solid and a liquid is called the specific latent heat of fusion
- For evaporating, boiling, and condensation the change between a liquid & gas is called the specific latent heat of vaporisation
infoNote
Formula: Energy for a change of state = mass × specific latent heat
Where:
- = energy for a change of state (Joules, J)
- = mass (kilogrammes, kg)
- = specific latent heat (Joules per kilogramme, J/kg)
Table of Variables
| Variable | Symbol | Units |
|---|---|---|
| Energy for Change of State | Joules (J) | |
| Mass | Kilogrammes (kg) | |
| Specific Latent Heat | Joules per kilogramme (J/kg) |
Measuring the change in temperature as ice melts and water heats
- Fill a beaker with crushed ice
- Place a thermometer into the beaker & record the temperature and current state of ice.
- Continue this till the water boils
- Plot a graph, with temperature against time.
