Specific Latent Heat

Question 1

What is the specific latent heat of a substance?

Answer 1

The amount of energy needed to change 1kg of the substance from one state to another with no change in temperature

Question 2

Specific latent heat equation

Answer 2

Thermal energy required (J) = mass (kg) x SLH (J/kg)

Question 3

SLH of fusion (Lf)

Answer 3

The amount of energy needed to change 1kg of the substance from solid to liquid with no change in temperature

Question 4

SLH of vaporisation (Lv)

Answer 4

The amount of energy needed to change 1kg of the substance from liquid to gas with no change in temperature

Question 5

How will a temperature-time graph look when melting ice an why?

Answer 5

1) line will initial rise upwards as the temperature of the ice increases
2) line will then flatten out as energy is being used to break the bonds within the solid
3) line will then rise upwards again as the temperature of the water increases
4) line will flatten out as energy is being used to break the bonds within the liquid
5) line will then rise again as the temperature of the gas increases