Latent heat

The heat required to change substance from one state of matter to another state of matter without any rise in temperature is called latent heat.

Water boils at . During this period the temperature remain at until all the water has been converted to steam . The same happens to Ice at . The temperature will remain at  until all the ice has been converted to water. Immediately all the ice has been converted to water, the temperature starts to rise . The same happens to water. Immediately all the water has been converted to steam the temperature starts to rise from

The heat gain during this period of conversion without any rise in temperature is  called latent heat.

we have

1. Latent heat of fusion
2. Latent heat of vaporisation

Latent heat of fusion

Latent heat of fusion is the quantity of heat energy require to convert the complete mass of the substance from its solid state to its liquid state without any rise in temperature.

  Latent heat of vaporisation

This is the heat energy requires to convert the complete mass of the substance from its liquid sate to vapour state without any rise in temperature.

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