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Jai Ganesh

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Registered: 2005-06-28

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Sublimation

Sublimation

Gist

Sublimation is the process where a substance transitions directly from a solid to a gas without becoming a liquid first. It is an endothermic process, meaning it requires energy, and can be seen in everyday examples like the disappearance of dry ice (CO2) and the evaporation of snow on a cold, dry day without melting. The opposite process, where a gas turns directly into a solid, is called deposition. 

Sublimation is the process where a solid turns directly into a gas without becoming a liquid first. Common examples include dry ice (solid carbon dioxide), which turns into gas at room temperature, and mothballs (naphthalene), which slowly release a gas that repels moths. 

Summary

Sublimation is the transition of a substance directly from the solid to the gas state, without passing through the liquid state. The verb form of sublimation is sublime, or less preferably, sublimate. Sublimate also refers to the product obtained by sublimation. The point at which sublimation occurs rapidly (for further details, see below) is called critical sublimation point, or simply sublimation point. 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.

Technically, all solids may sublime, though most sublime at extremely low rates that are hardly detectable under usual conditions. At normal pressures, most chemical compounds and elements possess three different states at different temperatures. In these cases, the transition from the solid to the gas state requires an intermediate liquid state. The pressure referred to is the partial pressure of the substance, not the total (e.g. atmospheric) pressure of the entire system. Thus, any solid can sublime if its vapour pressure is higher than the surrounding partial pressure of the same substance, and in some cases, sublimation occurs at an appreciable rate (e.g. water ice just below 0 °C).

For some substances, such as carbon and math, sublimation from solid state is much more achievable than evaporation from liquid state and it is difficult to obtain them as liquids. This is because the pressure of their triple point in its phase diagram (which corresponds to the lowest pressure at which the substance can exist as a liquid) is very high.

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. The enthalpy of sublimation (also called heat of sublimation) can be calculated by adding the enthalpy of fusion and the enthalpy of vaporization.

Details:

Definition of Sublimation

Sublimation is the process in which a solid directly changes into a gas without passing through the liquid phase. This process occurs when the temperature and pressure of the solid are raised to a point where the molecules have enough energy to break free from the intermolecular forces holding them in place and escape into the gas phase.

Sublimation Point

The sublimation point is the temperature and pressure at which the solid and gas phases of a substance are in equilibrium. At this point, the vapor pressure of the solid is equal to the pressure of the gas. The sublimation point is typically higher than the melting point of a substance.

Working Principle of Sublimation

Sublimation is the process in which a solid directly changes into a gas without passing through the liquid phase. This process occurs when the temperature and pressure of the solid are raised to a point where the molecules of the solid have enough energy to break free from the intermolecular forces holding them together and escape into the gas phase.

Sublimation is a process that occurs when a solid directly changes into a gas without passing through the liquid phase. This process has a number of applications, including freeze drying, desalination, purification, and 3D printing.

Characteristics of Sublimation

Sublimation is the process by which a solid directly changes into a gas without passing through the liquid phase. This process is the opposite of deposition, in which a gas directly changes into a solid. Sublimation is a physical change, meaning that the chemical composition of the substance does not change.

The following are some of the characteristics of sublimation:

* It occurs at a temperature and pressure below the triple point of the substance. The triple point is the temperature and pressure at which the three phases of a substance (solid, liquid, and gas) can coexist in equilibrium.
* It is a relatively slow process. This is because the molecules of a solid are more tightly packed together than the molecules of a gas, and it takes more energy to break these bonds.
* It is more common for substances with a high vapor pressure. Vapor pressure is the pressure exerted by the vapor of a substance when it is in equilibrium with its liquid or solid phase. Substances with a high vapor pressure are more likely to sublime because their molecules are more likely to escape from the solid or liquid phase.
* It can be used to purify substances. Sublimation can be used to separate a solid from impurities that have a lower vapor pressure. The solid is heated until it sublimes, and the impurities are left behind.
* It is used in a variety of applications. Sublimation is used in a variety of applications, including:

** Freeze-drying: Sublimation is used to remove water from food and other products.
** Dye sublimation printing: Sublimation is used to print images on fabrics and other materials.
** Vacuum coating: Sublimation is used to coat surfaces with a thin layer of metal or other material.

Examples of Sublimation

Some common examples of sublimation include:

* Dry ice (solid carbon dioxide) sublimes at atmospheric pressure. This is why dry ice “smokes” when it is exposed to air.
* Iodine sublimes at a temperature of 114°C (237°F). This is why iodine crystals disappear when they are heated.
* Naphthalene (mothballs) sublimes at a temperature of 80°C (176°F). This is why mothballs slowly disappear over time.

Sublimation is a unique and interesting physical change that has a variety of applications. By understanding the characteristics of sublimation, we can use this process to our advantage in a variety of ways.

Applications of Sublimation

Sublimation is the process of a solid turning directly into a gas without passing through the liquid phase. This process is used in a variety of applications, including:

Dye Sublimation Printing

Dye sublimation printing is a digital printing technology that uses heat to transfer dye onto materials such as paper, fabric, and plastic. This process is often used for creating high-quality prints on t-shirts, mugs, and other promotional items.

3D Printing

Sublimation is used in 3D printing to create objects from a digital file. In this process, a filament of plastic is heated until it melts and is then deposited layer by layer to create a three-dimensional object.

Food Processing

Sublimation is used in the food processing industry to remove moisture from food products. This process helps to preserve food and extend its shelf life.

Pharmaceuticals

Sublimation is used in the pharmaceutical industry to create drugs and other pharmaceutical products. This process allows for the precise control of the drug’s dosage and purity.

Electronics

Sublimation is used in the electronics industry to create thin films of metal and other materials. These films are used in a variety of electronic devices, such as transistors and capacitors.

Textile Printing

Sublimation printing is a digital printing technology that uses heat to transfer dye onto fabrics. This process is often used for creating high-quality prints on t-shirts, sportswear, and other textiles.

Other Applications

Sublimation is also used in a variety of other applications, including:

* Cosmetics: Sublimation is used to create makeup and other cosmetic products.
* Art: Sublimation is used to create prints on canvas, paper, and other materials.
* Industrial: Sublimation is used to create labels, decals, and other industrial products.

Sublimation is a versatile process that has a wide range of applications. It is a powerful tool that can be used to create high-quality products in a variety of industries.

Additional Information

Sublimation, in physics, is the conversion of a substance from the solid to the gaseous state without its becoming liquid. An example is the vaporization of frozen carbon dioxide (dry ice) at ordinary atmospheric pressure and temperature. The phenomenon is the result of vapour pressure and temperature relationships. Freeze-drying of food to preserve it involves sublimation of water from the food in a frozen state under high vacuum.

Sublimation is the process of changing a solid into a gas without passing through the liquid phase. To sublime a substance, a certain energy must be transferred to the substance via heat (q) or work (w). The energy needed to sublime a substance is particular to the substance's identity and temperature and must be sufficient to do all of the following:

* Excite the solid substance so that it reaches its maximum heat (energy) capacity (q) in the solid state.
* Sever all the intermolecular interactions holding the solid substance together
* Excite the unbonded atoms of the substance so that it reaches its minimum heat capacity in the gaseous state

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