10.3 Latent Heat

Match the terms with the definitions.

• Vaporisation

•  the heat needed to change 1 mole of the substance from a solid to a liquid at its melting point.

• Mole

• the process where a substance changes from a liquid or solid state into a gas or vapor.

• Latent Heat

• 6.02 x 10²³ particles

• Latent Heat of Vaporisation

•  the heat energy required to convert 1 mole of a liquid into a gas at its boiling point without a temperature change.

• Latent Heat of Fusion

• The amount of heat energy required to change the state of a substance without changing its temperature.

Label the following image

a

b

Latent Heat of Fusion

Latent Heat of Vaporisation

Label the following formula.
Note: this formula using mass rather than mole

a

b

c

Mass

Heat Absorbed or Released

Latent Heat Value

How much energy in kJ is required to completely vaporise 2.50 mol of water at 100 °C?
(The latent heat of vaporisation of water is 40.7 kJ/mol)

Mathematical Equivalence

ON

Answer explanation

If 203.5 kJ of heat is used to vaporise water at 100 °C, how many moles of water were vaporised?
(The latent heat of vaporisation of water is 40.7 kJ/mol)

Mathematical Equivalence

ON

Answer explanation

How many grams of water are vaporised using 122.1 kJ of heat at 100 °C?
(Molar mass of water = 18.0 g/mol, L=40.7 kJ mol^-1)

Mathematical Equivalence

ON

Answer explanation