What occurs when a solid changes directly into a gas without passing through a liquid state?

The process described in the question is sublimation, which occurs when a solid transitions directly into a gas without first becoming a liquid. An everyday example of sublimation is dry ice (solid carbon dioxide) which, at room temperature, changes from a solid into carbon dioxide gas without forming a liquid phase. This phenomenon is significant in various applications, including freeze-drying foods, where moisture is removed by sublimation, preserving the food's structure and nutritional content.

In contrast, condensation refers to the process where a gas turns into a liquid, melting involves a solid becoming a liquid, and freezing is the change of a liquid into a solid. Understanding sublimation is crucial in fields like respiratory care, where gas exchange and changes in state can play a role in equipment like nebulizers that may need to handle gases and aerosols efficiently.