Albert Teen

YOU ARE LEARNING:

Latent Heat

# Latent Heat

### Latent Heat

Latent heat is the energy required to enable a change of state to occur. This energy does not increase the temperature.

Laura is too hot in the house. She asks her mother to reduce the heat. Laura's father states that it is the temperature and not the heat which needs reducing. Is he correct, or is he just annoying?

Laura's persistent father decides to educate her. He asks: "When a body gains heat does it always rise in temperature?" What should Laura answer?

Laura's father explains to her that heat and temperature are two different things. Temperature is a measure of how hot or cold something is, whilst heat is a form of energy (thermal). It is possible for an object to gain thermal energy and the temperature to not rise.

Laura thinks she might have heard of this before. She thinks that the specific heat capacity of an object could be the reason that temperature could stay the same even though heat increases. Is she correct?

Now, Laura think again and she says that maybe latent heat is something to do with the energy required in changing states. Do you think she's right?

Laura's father explains that latent heat is the energy required to enable a change of state to occur. He reminds them that heat is a form of energy (another word for "thermal energy"). It is not the same as temperature.

Laura's mother enters the room carrying a cup of coffee which is giving off steam. Laura asks her father if this is a change of state. Is it?

Laura has a thought! She shouts out that this cup of coffee proves that the father is incorrect because as steam is given off from the coffee, the temperature is rising. Is she right?

Laura's father corrects her by explaining that at a change of state there is a change in internal energy stored as particles leave the substance or rejoin the substance. However, whilst this is caused by an increase in heat energy there is not a change of temperature as the state changes.

Laura's father leaves the room and asks them this question: The energy required for a change of state is called ...