Specific Latent Heat
Specific Latent Heat
Basic Definitions
- Specific latent heat is the energy required to change the state of a 1 kg substance without changing its temperature.
- The term ‘latent’ means hidden, implying energy put into or taken from a substance during a change of state doesn’t cause a temperature change.
- There are two types of specific latent heat: specific latent heat of fusion and specific latent heat of vaporisation.
Specific Latent Heat of Fusion
- Specific latent heat of fusion (L_f) refers to the energy needed to change a substance from solid to liquid at its melting point.
- For example, ice at 0 degrees Celsius needs to absorb a certain amount of energy to melt into water at 0 degrees Celsius.
Specific Latent Heat of Vaporisation
- Specific latent heat of vaporisation (L_v) is the energy required to change a substance from liquid to gas at its boiling point.
- For instance, water at 100 degrees Celsius needs to absorb a certain quantity of energy to become steam at the same temperature.
Calculating Energy Involving Specific Latent Heat
- The energy (E) involved in a change of state can be calculated using the formula: E = m × L, where ‘m’ is the mass and ‘L’ is the specific latent heat.
- Depending on the context, ‘L’ could represent L_f or L_v.
Real World Applications
- Understanding specific latent heat is crucial for many everyday applications such as refrigeration and heating systems.
Common Misconceptions
- A common confusion is thinking that temperature must change during a change of state. Remember that during a change of state, energy is used to break or form bonds between particles, not to raise the temperature.