Question

For any substance, why does the temperature remain constant during the change of state?

Answer 1

Hint: We must know that during phase transition of a matter, the heat supplied is fully utilized in overcoming the force of attraction present between particles.

Complete step by step solution:
We know that Temperature is a measure of the average kinetic energy of a particle. Also it is known that average kinetic energy of a gas molecule is directly proportional to its absolute temperature. In another way, we can say that the hotter the substance is, the faster its particles are moving on average.
We know that once the change of state of a substance begins or starts, the energy which is now supplied is being used up as latent heat. It means that it does not increase the kinetic energy of the particles and is used only to overcome the inter particles forces in that particular state and to bring about a change in state. In other words, it is only in the hidden form and not visible. Therefore, the temperature remains constant.
So, no heat is transferred outside and hence no temperature increases during the change of state. Hence, we can conclude that no temperature change will occur during change of state of matter as the energy supplied is used up in overcoming intermolecular force of attraction between molecules.

Note: During phase transition, the energy supplied is used up in overcoming intermolecular force of attraction present between molecules.
Heat plays an important role in changing matter from one phase to another.
Latent heat of fusion is the amount of heat given during phase transition from liquid to solid.
Latent heat of vaporization is the amount of heat given during phase transition from liquid to gas.