Why does the temperature of water not change while it is boiling?

Temperature is a measure of the average kinetic energy of the particles in a substance, while heat is the transfer of energy from one substance to another due to a temperature difference. When heat energy is transferred to water, the water molecules gain energy and move faster, increasing the water's temperature.

A phase change occurs when a substance changes its state, such as from a solid to a liquid or from a liquid to a gas. In the case of water boiling, the phase change is from a liquid to a gas (steam). Phase changes happen at specific temperatures called melting points or boiling points. For water, its boiling point at sea level is 100°C (212°F).

Latent heat is the amount of heat that is either absorbed or released when a substance undergoes a phase change without a change in temperature. For water, the latent heat of vaporization is the amount of heat energy required to change 1 kilogram of water at its boiling point into steam without changing its temperature.

When water reaches its boiling point (100°C at sea level), any further heat energy added will not increase its temperature. Instead, the heat energy is consumed in breaking the intermolecular bonds, and the water molecules gain sufficient energy to escape their liquid state and transform into steam. This is when the phase change occurs and the latent heat of vaporization comes into play. Since all the additional heat energy is being used for the phase change, the temperature of the water remains constant at its boiling point. Therefore, during the boiling process, the temperature of water does not change because the added heat energy is used to break the intermolecular bonds and facilitate the phase change from water to steam, rather than increasing the temperature.