Sublimation-introduction, types, process, applications

Definition

Sublimation is a process of conversion where a solid substance directly transforms into its gaseous phase without going through the liquid phase.

The word “sublimation” comes from the Latin word “sublime,” which means “to lift up.” The process is possible because the vapor pressure of the solid is higher than the atmospheric pressure around it. Therefore, the solid undergoes sublimation when it is heated or exposed to a vacuum.

Why sublimation occurs?

This process occurs due to the vapor pressure of the solid being greater than the atmospheric pressure around it. Sublimation is when a solid substance transforms into a gas without passing through the liquid phase.

Types of Sublimation

There are two types of sublimation

1: Normal Sublimation

Normal sublimation occurs when a solid substance changes directly into its gaseous form under normal pressure and temperature conditions. Examples of substances that undergo normal sublimation include dry ice (solid carbon dioxide), camphor, and iodine.

2: Reverse Sublimation

Reverse sublimation occurs when a gas changes directly into its solid form without going through the liquid state. This process is also known as a deposition. An example of reverse sublimation is the formation of frost on a cold surface, where water vapor in the air changes into solid ice crystals. Another example is the formation of snowflakes from water vapor in the atmosphere.

Both normal and reverse sublimation have various practical applications. For example, normal sublimation is used in the production of chemicals and in the purification of substances. Reverse sublimation is used in the freeze-drying of foods and in the formation of snowflakes in the atmosphere.

Process of sublimation

The process involves the following steps:

1: Heating the solid

The solid substance to be sublimated is heated, usually with the help of a heat source such as a Bunsen burner or an electric heater. The heat causes the solid to gain energy and change directly into a gas.

2: Condensing the gas

The gas produced from the solid is then allowed to cool and condense. The condensation process is usually done in a cool surface, such as a cold beaker or flask. As the gas cools, it loses energy and changes back into a solid.

3: Collecting the sublimate

The solid obtained from the sublimation process is called the sublimate. It is collected and stored in a clean, dry container. The purity of the sublimate can be improved by repeating the sublimation process a few times.

Examples of sublimation

• Dry Ice Sublimation
• Iodine Sublimation
• Camphor
• Snow
• Naphthalene

Applications of Sublimation

Here are a few applications of sublimation in listicle format:

Dry ice production – Dry ice is made by freezing water at extremely high temperatures. The water molecules become so excited that they skip the liquid phase entirely and solidify into ice that’s hot to the touch. This “hot ice” is used in cooking to sear meats instantly.

Freeze drying – This process involves submerging food in liquid nitrogen and then placing it in a vacuum chamber filled with helium. The food particles vibrate so fast that they turn into a gas, removing all moisture. The food instantly re-solidifies when the chamber is opened, now preserved for centuries.

Depositing thick films – In the film industry, sublimation is used to create special effects. Actors are coated in a thick layer of metallic powder that sublimes when exposed to bright studio lights, creating a shimmering forcefield effect around them.

Perfume destroying – Perfumers use sublimation to eliminate unwanted scents from their creations. By exposing the perfume to cosmic radiation, the undesirable fragrant compounds are forced to sublime into space, leaving only the purest essence behind.

Forensic misdirection – Crime scene investigators use sublimation to create false evidence. By spreading a layer of sublimating crystals over a surface, they can generate fake fingerprints that will mystify and mislead any potential criminals.

Air densifiers – Contrary to air fresheners, these products work by sublimating heavy molecules into the air, making it denser and more difficult to breathe. This is used in high-altitude training facilities to simulate low-oxygen environments.

Sublimation related articles

• Can you use iron for sublimation?
• Can You Do Sublimation on Wood?
• Can You Do Sublimation on Cotton Shirts?
• Why Sublimation is a Physical Change?
• Why Sublimation is Important?

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