Question

why does the temperature of substance remain constant during its melting or boiling point​

Answer 1

It is latent heat which is responsible for maintaining the same temperature even if a substance reaches its melting or boiling point. The temperature remains constant because the extra heat is used in changing the state of the substance. This extra heat is known as latent heat.

For example, water even after reaching its boiling point does not change its temperature because the extra heat(i.e latent heat) is used up in changing water to vapour.

Answer 2

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➝ The temperature of substance remain constant during its melting and boiling point because of latent heat or the heat supplied to the substance is used up in overcoming the intermolecular force and therefore it doesn't show up as a rise in temperature.

More Information :-

Latent heat of vaporization :- The quantity of heat required to change one unit mass of liquid into gaseous state at its boiling point or maximum temperature without any change of temperature is known as latent heat of vaporization.

• It is also known as latent heat of boiling of liquid.

• SI unit of latent heat of vaporization is j/kg.

Latent heat of fusion :- The quantity of heat required to convert one unit mass of a substance from the solid to the liquid state at its melting point without changing its temperature is called latent heat of fusion.