What is the term for a substance that changes directly from solid to gas?

The term for a substance that changes directly from solid to gas is sublimation. This process skips the liquid phase altogether. A common example of sublimation is dry ice, which is solid carbon dioxide; it transitions directly into carbon dioxide gas when exposed to ambient conditions. This unique phase change occurs under specific temperature and pressure conditions, allowing the substance to maintain its identity without becoming a liquid first.

Sublimation is an important concept in both physical chemistry and various applications, such as freeze drying and certain types of manufacturing processes, where control over phase transitions is crucial. Understanding sublimation helps to differentiate substances based on their behavior under varying environmental conditions, making it a vital topic in chemistry studies.