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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.
Solid carbon dioxide sublimes rapidly along the solid-gas boundary (sublimation point) below the triple point (e.g., at the temperature of −78.5 °C, at atmospheric pressure), whereas its melting into liquid CO 2 can occur along the solid-liquid boundary (melting point) at pressures and temperatures above the triple point (i.e., 5.1 atm, − ...
The form of the cooled surface often is a so-called cold finger which for very low-temperature sublimation may actually be cryogenically cooled. If the operation is a batch process , then the sublimed material can be collected from the cooled surface once heating ceases and the vacuum is released.
A typical phase diagram.The solid green line applies to most substances; the dashed green line gives the anomalous behavior of water. In thermodynamics, the triple point of a substance is the temperature and pressure at which the three phases (gas, liquid, and solid) of that substance coexist in thermodynamic equilibrium. [1]
Graph of temperature of phases of water heated from −100 °C to 200 °C – the dashed line example shows that melting and heating 1 kg of ice at −50 °C to water at 40 °C needs 600 kJ The terms sensible heat and latent heat refer to energy transferred between a body and its surroundings, defined by the occurrence or non-occurrence of ...
The low temperature and direct sublimation to a gas makes dry ice an effective coolant, since it is colder than water ice and leaves no residue as it changes state. [4] Its enthalpy of sublimation is 571 kJ/kg (25.2 kJ/mol, 136.5 calorie/g). Dry ice is non-polar, with a dipole moment of zero, so attractive intermolecular van der Waals forces ...
The sublimation sandwich method (also called the sublimation sandwich process and the sublimation sandwich technique) is a kind of physical vapor deposition used for creating man-made crystals. Silicon carbide is the most common crystal grown this way, though other crystals may also be created with it (notably gallium nitride ).
The commonly known phases solid, liquid and vapor are separated by phase boundaries, i.e. pressure–temperature combinations where two phases can coexist. At the triple point, all three phases can coexist. However, the liquid–vapor boundary terminates in an endpoint at some critical temperature T c and critical pressure p c. This is the ...