During the phase change of a substance, the temperature remains constant despite the continuous supply of heat. What is the primary reason for this…

Correct Option

The correct option is

The heat is consumed to overcome the forces of attraction between the particles.

Explanation

The phenomenon described is governed by the concept of Latent Heat. During a phase transition (such as melting or boiling), a substance absorbs heat energy without exhibiting a rise in temperature. This specific amount of heat is required to change the state of matter of the substance.

Detailed Analysis

• The supplied heat is dissipated into the surroundings immediately. is Incorrect: While some heat loss to the surroundings may occur in a non-ideal experimental setup, it is not the fundamental reason for the temperature constancy of the substance itself. In an isolated system, the temperature would still remain constant during the phase change.
• The heat is utilized to increase the average kinetic energy of the particles. is Incorrect: Temperature is a direct measure of the average kinetic energy of the particles. Since the temperature remains constant during the phase change, the average kinetic energy of the particles does not increase. The heat supplied does not contribute to particle speed during this specific interval.
• The heat is consumed to overcome the forces of attraction between the particles. is Correct: The heat supplied during a phase change is utilized to overcome the intermolecular forces of attraction holding the particles together. For example, during melting, energy is needed to weaken the rigid bonds of a solid structure; during boiling, energy is needed to completely break the attractive forces in a liquid. This energy increases the potential energy of the particles rather than their kinetic energy, resulting in a change of state without a change in temperature.
• The heat is absorbed by the container holding the substance. is Incorrect: Although the container absorbs heat until it reaches thermal equilibrium with the substance, this is a peripheral factor. It does not explain the thermodynamic behavior of the substance undergoing the phase change.

Key Takeaway

Latent Heat is the energy absorbed or released during a phase change. It is used exclusively to overcome intermolecular forces (increasing potential energy), leaving the temperature (average kinetic energy) constant until the transition is complete.