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The sublimation that occurs at the solid-gas boundary (critical sublimation point) (corresponding to boiling in vaporization) may be called rapid sublimation, and the substance sublimes rapidly. The words "gradual" and "rapid" have acquired special meanings in this context and no longer describe the rate of sublimation. [citation needed]
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.
The energy required to remove one or more electrons to make a cation is a sum of successive ionization energies; for example, the energy needed to form Mg 2+ is the ionization energy required to remove the first electron from Mg, plus the ionization energy required to remove the second electron from Mg +.
These names describe the direction of energy flow when changing from one phase to the next: from solid to liquid, and liquid to gas. In both cases the change is endothermic, meaning that the system absorbs energy. For example, when water evaporates, an input of energy is required for the water molecules to overcome the forces of attraction ...
The reaction of molybdenum dioxide with the transporting agent iodine is an exothermic process, thus the MoO 2 migrates from the cooler end (700 °C) to the hotter end (900 °C): MoO 2 + I 2 ⇌ MoO 2 I 2 ΔH rxn < 0 (exothermic) Using 10 milligrams of iodine for 4 grams of the solid, the process requires several days.
A small piece of rapidly melting solid argon shows two concurrent phase changes. The transition from solid to liquid, and gas to liquid (shown by the white condensed water vapour). Other phase changes include: Transition to a mesophase between solid and liquid, such as one of the "liquid crystal" phases.
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Volatility can also describe the tendency of a vapor to condense into a liquid or solid; less volatile substances will more readily condense from a vapor than highly volatile ones. [1] Differences in volatility can be observed by comparing how fast substances within a group evaporate (or sublimate in the case of solids) when exposed to the ...