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

The process in which a solid changes directly into a gas is termed sublimation. This phenomenon occurs without the substance transitioning through a liquid state. An everyday example of sublimation is dry ice (solid carbon dioxide), which, when exposed to heat, transforms directly into carbon dioxide gas without becoming liquid first.

In sublimation, the molecules of the solid gain enough energy to overcome the intermolecular forces holding them in place, allowing them to enter the gaseous phase directly. Conditions such as temperature and atmospheric pressure can influence this process; for instance, sublimation is more common at lower atmospheric pressures.

Understanding sublimation is crucial in various fields such as chemistry, meteorology, and environmental science, as this process plays a role in phenomena like the sublimation of ice in polar regions or the use of freeze-drying in food preservation.