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How does boiling absorb heat at a constant temperature?

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heating In a thermoelectric generating system a heat source—usually fueled by coal, oil, or gas—is used within a boiler to convert water to high-pressure steam. The steam expands and turns the blades of a turbine, which turns the armature of a generator, producing electric power. A condenser converts any remaining steam to water, and a pump returns the water to the boiler.

Boiling absorbs heat at a constant temperature because the energy added to the system is consumed as latent heat of vaporization rather than increasing the kinetic energy of the molecules.1

During the phase transition from liquid to gas, the substance must overcome the attractive forces that maintain the liquid's cohesion. All heat supplied to the substance during this process is utilized to break these long-range intermolecular bonds and facilitate the transition to a disordered gaseous state. Because this energy is entirely dedicated to the phase change, the temperature of the liquid remains constant until the entire mass has vaporized.12

In this state, the escaping vapour molecules carry away the absorbed thermal energy, which is why the temperature does not rise even as additional heat is applied. This process occurs at the boiling point, the temperature at which the liquid's vapour pressure equals the pressure exerted by the surrounding environment.12