The Particle Model

YOU ARE LEARNING:

Specific Latent Heat

Specific latent heat of a substance is the amount of energy needed to change 1 Kg of a substance from one state to another without changing its temperature.

Is it correct that all changes of state involve energy transfer?

But some changes of state involve cooling. So how can energy be transferred?

When an object is heated, the energy is used for breaking the bonds rather than raising the temperature. This is why the temperature does not increase in a change of state.

When an object is cooled, new bonds are formed, and energy is released.

What term do we use to describe the amount of energy needed to change 1 Kg of a substance from one state to another, without changing its temperature?

Specific latent heat of a substance is the amount of energy needed to change 1 Kg of a substance from one state to another without changing its temperature.

Different factors can affect the specific latent heat. Select all the options below which you think would do that.

You can select multiple answers

The factors which affect the specific latent heat of a substance are type of substance and the change of state. There are different names for the specific latent heat for the different changes of state.

Which of the following would be the correct name for specific latent heat involving change of state from solid to liquid and vice versa?

What do you think we call the specific latent heat for a change of state from a liquid to a gas?

You can work out the energy needed for a change of state for a given mass of a substance using a formula. Which of the following would be the correct formula?

So the formula for the energy needed for a change of state is this one: $energy (E)=mass(m)\times specific\space latent\space heat (l)$

This can be written as $E=ml$ . Remember that energy is measure in Joules (J), mass in Kg and specific latent heat in J/Kg.