What is the process called when a solid changes directly into a gas?

The process where a solid changes directly into a gas is known as sublimation. This occurs when the particles in a solid gain enough energy, typically through the addition of heat, to overcome their intermolecular forces and transition into the gas phase without first becoming a liquid. A common example of sublimation is the transformation of dry ice (solid carbon dioxide) directly into carbon dioxide gas, bypassing the liquid state entirely.

In contrast, evaporation refers to the transition of a liquid to a gas, while condensation describes the process of a gas turning into a liquid. Melting involves the phase change from a solid to a liquid. Each of these terms describes different transitions involving solids, liquids, and gases, highlighting why sublimation is distinct in its direct solid-to-gas transformation.