Sublimation

Definition

Sublimation is the phase change where a substance transitions directly from a solid to a gas without passing through the liquid phase. It occurs when the molecules of the solid gain enough energy to overcome intermolecular forces and enter the gas phase.

5 Must Know Facts For Your Next Test

1. Sublimation requires an input of energy, known as latent heat, which is absorbed by the substance as it changes phase.
2. Common examples of substances that undergo sublimation include dry ice (solid CO2) and iodine crystals.
3. The process can be described using the Clausius-Clapeyron equation, which relates the pressure and temperature during phase transitions.
4. Sublimation occurs under certain conditions of temperature and pressure, typically at low pressures or high temperatures relative to the substance’s triple point.
5. In thermodynamics, sublimation is an endothermic process because it absorbs heat from its surroundings.

Review Questions

• What is required for a substance to undergo sublimation?
• Give two examples of substances that commonly sublimate.
• Why is sublimation considered an endothermic process?

Related terms

Latent Heat:

The amount of heat absorbed or released by a substance during a phase change without changing its temperature.

Triple Point:

The unique set of conditions at which all three phases (solid, liquid, gas) of a substance coexist in thermodynamic equilibrium.

Clausius-Clapeyron Equation: An equation that describes the relationship between vapor pressure and temperature for phase transitions.