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The process of conversion of solid directly into gas is called ____________.
Evaporation
Condensation
Sublimation
Deposition
Sublimation
Sublimation is the phase transition in which a substance changes directly from the solid state to the gaseous state without passing through the intermediate liquid phase. This occurs when the vapor pressure of the solid exceeds the atmospheric pressure at a given temperature.
Sublimation is the phase transition in which a substance changes directly from the solid state to the gaseous state without passing through the intermediate liquid phase. This occurs when the vapor pressure of the solid exceeds the atmospheric pressure at a given temperature.
Think of a block of dry ice (CO2тАЛ) left on a table; instead of melting into a puddle, it slowly disappears into thin air, creating a fog as it turns into carbon dioxide gas.
SUB (below/under) + LIME (boundary) = jumping the liquid boundary.
Q=m├ЧLsтАЛ тАФ where Q is the heat absorbed, m is the mass, and LsтАЛ is the latent heat of sublimation.
This process occurs when the molecules of a solid acquire sufficient thermal energy to overcome the intermolecular forces holding them in a rigid lattice structure, allowing them to escape directly into the vapor phase. It is an endothermic process, requiring the absorption of latent heat of sublimation.
Sublimation is an endothermic phase transition.
Common substances exhibiting this are naphthalene balls, dry ice (CO2тАЛ), and iodine.
The reverse process of gas turning directly into solid is called deposition.
Used for purification of volatile substances
Effective in freeze-drying (lyophilization) to preserve sensitive biological materials
Requires controlled temperature and pressure conditions
Not all substances can sublime under standard atmospheric pressure
Naphthalene balls used as moth repellents
Freeze-drying of food and pharmaceuticals
Standard atmospheric pressure is 1.013├Ч105Pa.
Option A (Evaporation) is liquid to gas, Option B (Condensation) is gas to liquid, and Option D (Deposition) is gas to solid.
C is correct тАФ Sublimation is the direct transition of a substance from solid phase to gas phase.
Always remember the phase diagram: Sublimation happens below the triple point pressure on a PтИТT diagram for most substances.
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