Final answer:
During a phase change, the energy is used to break the bonds between molecules rather than increasing the kinetic energy of the particles, resulting in no change in temperature. Once the phase change is complete, the kinetic energy of the particles can increase, leading to a rise in temperature.
Step-by-step explanation:
During a phase change, the temperature remains constant because the energy supplied is used to break the bonds between molecules, rather than increasing the kinetic energy of the particles. This is known as latent heat, where the energy enters or leaves the system without causing a temperature change.
When a solid is heated, the added energy breaks the intermolecular bonds, transforming it into a liquid. Similarly, when a liquid is heated, the energy breaks the intermolecular forces and changes it into a gas. In both cases, the energy is used to overcome the attractive forces between the molecules, rather than increasing their kinetic energy.
This phenomenon occurs because the potential energy of the particles increases during a phase change, while their kinetic energy remains constant. Once the phase change is complete, the kinetic energy of the particles can increase again, resulting in a rise in temperature.