Bypassing the liquid phase, sublimation is the process by which a solid transforms instantly into a gas. This happens when the forces of attraction between the particles in a solid are overcome, resulting in the particles breaking apart and forming a gas.
The process through which dry ice, or solid carbon dioxide, sublimes, is a typical illustration of sublimation. Dry ice is maintained at a temperature of -78.5 °C, which is significantly below its typical freezing point of -56.6 °C. The solid carbon dioxide particles have sufficient energy at this temperature to separate and become a gas directly, skipping the liquid phase.
The mechanism by which solid iodine sublimes is another illustration of sublimation. Iodine has a relatively low boiling point of 157.2 degrees Celsius, which means that it has sufficient energy to disintegrate and create a gas even at ambient temperature. As a result, the solid iodine may eventually vanish and emit a distinctive purple vapor.
Other solid materials, such as frozen water, naphthalene (mothballs), and certain kinds of chemicals, may also sublimate in addition to these examples.
