Sublimation in Chemistry
The sublimation of chunk of dry ice kept in the bowl
Image credit: pixabay.com
Any matter that exists around us could be in either of the four phases – solid, liquid, gas and plasma. We can see that matters can change from a present state to another with the change in external condition such as temperature or pressure without changing the identity of the matter. This process is called phase transition or physical change in state of the matter.
One of the different types of phase transition is sublimation. Sublimation can be defined as the transition of a matter directly from the solid state to the gaseous state without initially changing to the liquid state. It is an endothermic (absorption of heat) process that occurs when both the temperature and pressure is below the triple point of the matter under phase transition in its phase diagram.
The phenomenon of sublimation can be seen more readily in the regions with dry gusts of wind and relatively low humidity at higher altitude, where the atmospheric pressure decreases with increase in altitude helping in the transition of mountain ice/snow directly into vapour. The reverse of sublimation is called deposition, a phase transition, where gases transit directly to the solid phase.
Naphthalene, iodine, dry ice, ammonium chloride and camphor are some of the compounds that show the phenomenon of sublimation.
Last Updated: Jan 30, 2019