Vocabulary

• Melting – to make or become liquefied by adding heat. (solid to liquid)
• Freezing – To make or becoming a solid by taking away heat. (liquid to solid)
• Evaporation – To make or become gaseous by adding heat. (liquid to gas)
• Sublimation – Phase change from solid to gas
• Condensation – Phase change from gas to liquid

What is latent heat ?

• Latent heat is defined as the heat absorbed or released when a substance changes its physical state completely at constant temperature.

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• Heat of vaporization - The energy required to change a gram of a liquid into the gaseous state at the boiling point 

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• Heat of fusion - The energy required to change a gram of a substance from the solid to the liquid state without changing its temperature

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During melting, the heat absorbed is used to break up the bonds between the particles. The particles are free from their fixed positions and are able to vibrate and move among each other.

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When liquid boils, the heat absorbed is used to completely break the bonds of the particles and also to do work against atmospheric pressure when the gaseous vapor expands into the atmosphere.

SOLID

LIQUID

GAS

SOLID AND LIQUID

LIQUID AND GAS

• Molecules are held together tightly.
• When heated, it gain energy and vibrate about their fixed position at greater speeds and amplitudes.

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• The liquid vaporizes completely into gas.

• The liquid temperature rises.
• Molecules begin to moves faster and randomly.

• The liquid starts to boil
• Latent heat of vaporization is absorbed the liquid.

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• The solid begin to melt.
• Latent heat of fusion is absorbed by the solid.
• The molecules are freed from their fixed positions and are able to move about.

LATENT HEAT

• SOLID LIQUID

CHANGE IN STATE

3 STATES OF MATTER

SOLID

LIQUIDS

GASES

LATENT HEAT OF

VAPORIZATION

LATEN HEAT

OF FUSION

LATENT HEAT IS ABSORBED

LATENT HEAT IS RELEASED

LATENT HEAT IS ABSORBED

LATENT HEAT IS RELEASED

• LIQUID GAS