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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 ...
Notable examples include sublimation of dry ice at room temperature and atmospheric pressure, and that of solid iodine with heating. The reverse process of sublimation is deposition (also called desublimation), in which a substance passes directly from a gas to a solid phase, without passing through the liquid state. [4]
Another version involves filling the device with a cold material (examples: ice, dry ice or a mixture such as dry ice/acetone or ice/water). [1] Typically a cold finger is used in a sublimation apparatus, [2] or can be used as a compact version of a condenser in either reflux reaction or distillation apparatus.
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.
Freeze drying, also known as lyophilization or cryodesiccation, is a low temperature dehydration process [1] that involves freezing the product and lowering pressure, thereby removing the ice by sublimation. [2] This is in contrast to dehydration by most conventional methods that evaporate water using heat. [3]
Underwater explosions using dry ice and liquid nitrogen are captured in high definition slow motion by The Backyard Scientist.
The dry ice color show is usually performed in classrooms to demonstrate the properties of acids and bases, their effect on pH indicators, and the sublimation of dry ice. Setup is simple and generally involves only minor hazards, the main one being the low temperature of dry ice, which can cause frostbite upon skin contact.
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