Sublimation Definition (Phase Transition in Chemistry)

Sublimation Definition

Sublimation is the transition from the solid phase to the gas phase without passing through an intermediate liquid phase. This endothermic phase transition occurs at temperatures and pressures below the triple point.

The term "sublimation" only applies to physical changes of state and not to the transformation of a solid into a gas during a chemical reaction. For example, when candle wax undergoes combustion, the paraffin is vaporized and reacts with oxygen to produce carbon dioxide and water. This is not sublimation.

The opposite process of sublimation—where a gas undergoes a phase change into solid form—is called deposition or desublimation.

Sublimation Examples

• Dry ice is solid carbon dioxide. At room temperature and pressure, it sublimates into carbon dioxide vapor.
• Freezer burn results from the sublimation of ice into water vapor.
• At the right temperature, the elements iodine and arsenic will sublimate from solid form into gaseous form.
• Naphthalene, a chemical commonly used in mothballs, readily sublimates at room temperature and pressure.
• Water ice will sublimate, although more slowly than dry ice. The effect can be seen over snowfields when the sun is out but the temperature is cold.

Practical Applications of Sublimation

• Sublimation and erosion cause ablation, a process that wears down glaciers.
• Sublimation of iodine may be used to reveal latent fingerprints on paper.
• Sublimation is used to purify compounds. It is especially useful for organic compounds.
• Because dry ice sublimates so readily, the compound is used to produce fog effects.