QS Study

Latent heat of fusion:

We know, when the temperature of a solid reaches the melting point due to application of heat then the temperature remain unchanged until all the substances transform into liquid. Here the amount of heat required to transform the solid into liquid is nothing but latent heat of fusion.

This heat energy does not change the temperature but is used to loosen the intermolecular bond of the molecules of the substances.

Latent heat of vaporization:

If heat is applied to a liquid and its temperature reaches at the boiling point then whatever amount of heat is applied the temperature will remain unchanged until all the liquid is converted into vapor state. Here the amount of heat required to convert the liquid into vapor state is called latent heat of vaporization.

Evaporation produces cooling: In summer days the water kept in a new earthen pitcher becomes cold. Uncountable numbers of pores are there on the body of an earthen pitcher. Through these pores water seeps out and evaporates. The needed amount of latent heat is provided by the water of the pitcher and as such the water becomes cold.

Water kept in the glass or brass vessel does not become cold. Because the body of this kind of container has no pore and there is no possibility of evaporation.

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