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

The process in which a solid turns directly into a gas is known as sublimation. This occurs when the molecules in a solid gain enough energy to overcome intermolecular forces, bypassing the liquid state entirely.

A common example of sublimation can be observed with dry ice (solid carbon dioxide), which transitions directly from a solid to carbon dioxide gas without becoming liquid under normal atmospheric conditions. This transition is often illustrated in experiments where dry ice produces fog as it sublimates in air.

In contrast, condensation refers to the process where gas turns into a liquid, while evaporation and vaporization pertain to the transition from liquid to gas. Therefore, sublimation is uniquely defined by the direct conversion from solid to gas, making it the correct terminology for this specific phase change.