HAZMAT Technician Practice Exam

Which process describes sublimation?

1. A change from solid to liquid

2. A change from solid to gas

3. A change from liquid to gas

4. A change from gas to solid

The correct answer is: A change from solid to gas

Sublimation is the process in which a substance transitions from a solid state directly to a gaseous state without passing through the liquid state. This occurs under conditions of temperature and pressure where the solid is heated, resulting in the molecules gaining enough energy to break free from their fixed positions and enter the vapor phase. A common example of sublimation is the transformation of dry ice (solid carbon dioxide) directly into carbon dioxide gas when exposed to room temperature. Understanding this concept is crucial, especially in HAZMAT scenarios, as certain hazardous materials may sublimate and present a gas hazard without the presence of a liquid phase, affecting containment and response strategies.