Sublimation is a change from a solid to gas.

Study for the Medical Chemistry Test. Explore multiple choice questions with hints and explanations. Get exam-ready with engaging quizzes and comprehensive study materials.

Sublimation is a direct solid-to-gas phase transition, bypassing the liquid state. This happens when the solid’s molecules gain enough energy (or the surrounding pressure is low enough) that they enter the vapor phase without melting. Dry ice and iodine crystals are classic examples that sublimate at room temperature. Because the substance goes straight from solid to gas, it is not melting (solid to liquid), not deposition (gas to solid), and not vaporization from liquid to gas. Sublimation is typically energy-intensive, since it requires overcoming the forces holding the solid together to form vapor.