Answers to GCSE Latent Heat

Practice Questions

1.State the definition of latent heat

Latent heat is the energy needed to change the state of a substance.

2.Use the graph below to anwer the following question.

Suggest why the horizontal line for latent heat of vaporisation is longer than the horizontal line for latent heat of fusion

For this substance more energy needs to be supplied for vaporisation compared to fusion. Therefore latent heat of vaporisation is a larger value than latent heat of fusion.

3. Explain  how  both the intermolecular forces and internal energy of water particles change as steam condenses to form liquid water

As the steam is cooled the internal energy of the water particles will decrease. As the water particles move closer together and decrease in speed, intermolecular forces will form between them as steam condenses to form liquid water.