Which process involves the highest energy requirement during phase changes?

The process that involves the highest energy requirement during phase changes is the transition from liquid to gas. This phase change, known as evaporation or boiling, requires a significant amount of energy, referred to as the latent heat of vaporization. During this process, molecules in the liquid state gain enough energy to overcome the intermolecular forces that hold them together, allowing them to enter the gaseous state.

When a liquid is heated, its molecules move faster as they absorb energy. Once sufficient energy is reached, some molecules can break free from the liquid’s surface and enter the gas phase. This energy requirement is higher compared to transitions like melting (solid to liquid), which requires only the latent heat of fusion, or freezing (liquid to solid), which releases energy. Hence, the transition from liquid to gas distinctly necessitates more energy input, making it the phase change with the highest energy requirement.