Uncommon Phase Transitions

During class this week, we learned about the different states of matter and how the characteristics of atoms change as matter changes its phase. Some of these phase transitions were familiar to me. Melting, the transition from a solid phase to a liquid phase. Freezing, the transition from a liquid phase to a solid phase. Vaporization, the transition from a liquid phase to a gas phase. Condensation, the transition of a gas phase to a liquid phase. I have seen condensation on the side of my soda can, watched water evaporate on hot days, seen my ice cream melt, and all of Lake Waban is frozen at the moment. What I did not know, is that there are other phase transitions. I believed that in order for a solid to become a gas, it would first have to melt into a liquid. This is not true. There is a phase transition called sublimation which is the direct transition of a solid into a gas. Sublimation requires additional energy and is an endothermic change, which means that it absorbs energy from its surrounding in the form of heat. The opposite of sublimation is also possible and it is called deposition. Deposition is the direct transition of a gas into a solid. Deposition is an exothermic process, which releases energy in the form of heat. An example of deposition is when snow forms in clouds as gaseous water vapor transitions to solid snow. With sublimation and deposition, it is possible for any state of matter to transition to any other state of matter, gas, liquid, or solid.