SDSU Chemistry Placement Practice Test

The process of a solid turning directly into a gas is known as sublimation. This phenomenon occurs under certain conditions, typically at low pressures or high temperatures, where the solid does not pass through the liquid phase before becoming a gas. Common examples of sublimation include dry ice (solid carbon dioxide) transitioning directly to carbon dioxide gas and the sublimation of ice in extremely cold but low-pressure environments, such as in a deep freeze or high-altitude settings.

Vaporization, on the other hand, refers to the process of a liquid turning into a gas, which includes both evaporation (occurring at the surface of a liquid at any temperature) and boiling (occurring throughout the entire liquid at a specific temperature). Condensation is the opposite of vaporization, where a gas turns into a liquid. These distinctions highlight why sublimation is the correct answer for the process involving a solid directly transitioning to a gas.