Question

How does the addition of heat to a substance at its melting point affect its average kinetic energy?

Answer 1

Adding heat to a substance at its melting point is used for the phase change and does not increase its average kinetic energy, which remains constant during the process.

Step-by-step explanation:

When heat is added to a substance at its melting point, it does not increase the average kinetic energy (KE) of the particles but rather is used to break the bonds between them, enabling the phase change from solid to liquid. According to the kinetic-molecular theory, the temperature of a substance is related to the average kinetic energy of its particles. However, during a phase change like melting, the temperature remains constant as the substance absorbs heat energy to weaken and break intermolecular bonds without increasing the motion (kinetic energy) of the particles.

Answer 2

At the melting point, the heat added is used to break the attractive intermolecular forces of the solid instead of increasing kinetic energy, and therefore the temperature remains constant.