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How does melting 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.

When a pure crystalline solid reaches its melting point, it undergoes a phase change from solid to liquid. During this process, the temperature remains constant because the energy being added is not used to increase the kinetic energy of the particles—which would raise the temperature—but is instead absorbed as latent heat, specifically the heat of fusion.123

This absorbed energy is required to perform the work necessary to overcome the attractive forces holding the atoms or molecules in their stable, ordered crystalline lattice positions. By providing this energy, the substance transitions into a more disordered liquid state where particles are free to move, even though they remain cohesive. Once the entire mass of the solid has melted, any additional heat applied will then contribute to increasing the temperature of the resulting liquid.23