what is sublimation???
Answers
→The term sublimation is the passage or the transformation or conversion that substances undergo when passing from one state to another, for example from a solid substance to gas.
→We can define sublimation as the transition of a substance from the solid phase to the gaseous phase without changing into the liquid phase. This process is an endothermic phase transition that occurs at a temperature and pressure below the triple point of the substance. Desublimation or deposition is the reverse of this process in which a gas is directly converted into solid-state.
→The best example of sublimation is dry ice which is a frozen form of carbon dioxide. When dry ice gets exposed to air, dry ice directly changes its phase from solid-state to gaseous state which is visible as fog. Frozen carbon dioxide in its gaseous state is more stable than in its solid-state.
→Another well-known example of sublimation is naphthalene which is an organic compound. Naphthalene is usually found in pesticides such as mothball. This organic compound sublimes due to the presence of non-polar molecules that are held by Van Der Waals intermolecular forces. At a temperature of 176F naphthalene sublimes to form vapours. It desublimates at cool surfaces to form needle-like crystals.
Answer:
Answer:Sublimation is the transition of a substance directly from the solid to the gas state,without passing through the liquid state. Sublimation is an endothermic process that occurs at temperatures and pressures below a substance's triple point in its phase diagram, which corresponds to the lowest pressure at which the substance can exist as a liquid. The reverse process of sublimation is deposition or desublimation, in which a substance passes directly from a gas to a solid phase. Sublimation has also been used as a generic term to describe a solid-to-gas transition (sublimation) followed by a gas-to-solid transition (deposition). While vaporization from liquid to gas occurs as evaporation from the surface if it occurs below the boiling point of the liquid, and as boiling with formation of bubbles in the interior of the liquid if it occurs at the boiling point, there is no such distinction for the solid-to-gas transition which always occurs as sublimation from the surface.At normal pressures, most chemical compounds and elements possess three different states at different temperatures. In these cases, the transition from the solid to the gaseous state requires an intermediate liquid state. The pressure referred to is the partial pressure of the substance, not the total (e.g. atmospheric) pressure of the entire system. So, all solids that possess an appreciable vapour pressure at a certain temperature usually can sublime in air (e.g. water ice just below 0 °C). For some substances, such as carbon and arsenic, sublimation is much easier than evaporation from the melt, because the pressure of their triple point is very high, and it is difficult to obtain them as liquids.