6.5 Specific Latent Heat

Question 1

Describe how energy is transferred when substances change state by melting/boiling

Answer 1

When a substance is melting or boiling, energy is transferred to the potential energy stores of the particles as the energy is used to break bonds between particles and move the particles further apart. So the temperature doesn’t change but the internal energy increases.

Question 2

Why is there flat spots on the heating graph at the melting and boiling points?

Answer 2

Energy is being transferred but the temperature does not change

Question 3

Describe how energy is transferred when a substance changes state by condensing/freezing

Answer 3

When a substance is condensing or freezing, bonds are forming between particles, which releases energy. This means the internal energy decreases but the temperature doesn’t go down until all the substance has turned into a liquid (condensing) or a solid (freezing).

Question 4

What is specific latent heat?

Answer 4

The specific latent heat is the required to change 1kg of a particular substance from one state to another, without a change in temperature.

Question 5

The specific latent heat of ______ refers to when a substance changes from a solid to a liquid (or vice versa)

Answer 5

fusion

Question 6

The specific latent heat of ___________ refers to when a substance changes from a liquid to a gas (or vice versa)

Answer 6

vaporisation