Latent Heat of Vaporisation for Water

States of Matter

• Particles from the bulk of a liquid gain enough energy to change into the vapour state, with a temperature of 373 K (100°C) for water.

Latent Heat of Vaporisation

• Latent heat of vaporisation is the heat energy required to change 1 kg of a liquid to gas at atmospheric pressure at its boiling point.
• It is the energy absorbed by particles in steam to change from liquid to vapour state.

Boiling and Evaporation

• Boiling is a bulk phenomenon where particles from the bulk of the liquid change into vapour state.
• Evaporation is a surface phenomenon where particles from the surface gain enough energy to change into vapour state.
• Evaporation causes cooling and its rate depends on surface area, temperature, humidity, and wind speed.

Temperature Conversion

• 0°C = 273 K, and to convert Celsius to Kelvin, add 273 to the Celsius temperature.
• To convert Kelvin to Celsius, subtract 273 from the Kelvin temperature.

Sublimation and Deposition

• Sublimation is a change of state directly from solid to gas without changing into liquid state.
• Deposition is a change of state directly from gaseous state to solid state without going through liquid state.
• Examples of sublimation and deposition include camphor and solid carbon dioxide (dry ice).

Effect of Change of Pressure

• Applying pressure and reducing temperature can liquefy gases.
• Pressure and temperature determine the state of a substance, whether it will be solid, liquid, or gas.
• Decreasing pressure can change a solid directly into a gas, as seen in solid carbon dioxide (dry ice).