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Sublimation is caused by the absorption of heat which provides enough energy for some molecules to overcome the attractive forces of their neighbors and escape into the vapor phase. Since the process requires additional energy, sublimation is an endothermic change.
into exo and endo ring closures, depending whether the bond broken during the ring closure is inside (endo) or outside (exo) the ring that is being formed; into tet, trig and dig geometry of the atom being attacked, depending on whether this electrophilic carbon is tetrahedral (sp 3 hybridised), trigonal (sp 2 hybridised) or diagonal (sp ...
In thermodynamics, the enthalpy of sublimation, or heat of sublimation, is the heat required to sublimate (change from solid to gas) one mole of a substance at a given combination of temperature and pressure, usually standard temperature and pressure (STP). It is equal to the cohesive energy of the solid.
H sub, the standard enthalpy of atomization (or sublimation) of solid lithium. IE Li, the first ionization energy of gaseous lithium. B(F–F), the standard enthalpy of atomization (or bond energy) of fluorine gas. EA F, the electron affinity of a fluorine atom. U L, the lattice energy of lithium fluoride.
Endo and exo transition states for cyclopentadiene adding to acrolein; endo/exo product ratio for this and various other dienophiles. Diels–Alder reactions in which adjacent stereocenters are generated at the two ends of the newly formed single bonds imply two different possible stereochemical outcomes.
A sublimatory [1] [2] or sublimation apparatus is equipment, commonly laboratory glassware, for purification of compounds by selective sublimation. In principle, the operation resembles purification by distillation , except that the products do not pass through a liquid phase .
another definition sublimation is a type of evaporation in which a solid changes directly to a gas without going through a liquid state. The definition in the article should read: " Sublimation of an element or compound is the direct transition from the solid to the gas phase".
The opposite of an endothermic process is an exothermic process, one that releases or "gives out" energy, usually in the form of heat and sometimes as electrical energy. [1] Thus, endo in endothermic refers to energy or heat going in, and exo in exothermic refers to energy or heat going out. In each term (endothermic and exothermic) the prefix ...