What is Sublimation? 

Sublimation is the passage, transformation, or conversion of the transition from the solid phase to the gas phase without passing or changing through an intermediate liquid phase. This process is an endothermic phase transition that occurs at a temperature and pressure below the substance’s triple point.

The term sublimation only applies to the physical change of state of a substance and not to the transformation of a solid into a gas during a chemical reaction. For example, when candle wax undergoes combustion in the presence of air, the paraffin gets vaporised and reacts with oxygen in the atmosphere to produce carbon dioxide and water. This process is not called sublimation. The reverse sublimation process is called deposition or desublimation, in which gas is directly converted into solid-state without passing through an intermediate liquid phase. It is an exothermic phase change that occurs at temperatures and pressures below a substance’s triple point in its phase diagram. For example, frost formation occurs on window surfaces during the winter seasons.

Examples of Sublimation

1. The best example of sublimation is dry ice. Dry ice is solid carbon dioxide. At room temperature and pressure, it sublimates into carbon dioxide vapour. When dry ice is exposed to air, it changes its phase from a solid state to a gaseous state, visible as fog.

2. Another well-known example of sublimation is naphthalene which is an organic compound. Naphthalene is usually found in pesticides such as mothballs. At room temperature and pressure, camphor converts directly into its gaseous state without converting into a liquid state.

3. Freezer burn results from the sublimation of ice into water vapour. For example,zer burn is caused by water sublimation from ice crystals at the meat’s surface into the dryzer air.

4. At the right temperature, the elements iodine and arsenic will sublimate from solid form into gaseous form.

5. Water ice will sublimate, although more slowly than dry ice. The effect can be seen over snowfields when the sun is out, but the temperature is cold.

6. Anthracene is another example that is sublime when present in solid-state and possess a sublimation process by directly converting into the gaseous state without changing into a liquid state.

7. At very low pressure, compounds containing zinc also undergo sublimation.

8. At the arctic and antarctic poles, frozen water at 0 ^oC sublimes to escape into the atmosphere. This phenomenon is called polar evaporation.

9. Frost formation: Water vapour undergoes desublimation at very cold temperatures, forming ice crystals on surfaces called frost.

10. Corrosive gas sublimation: Some metallic vapours, like mercuric chloride, will inversely sublimate, a common degrading step in alchemical activities. 

Applications of Sublimations

The sublimation process has a wide range of applications in the textile, polymer, and pharma industries.

1. In the forensic sciences, sublimation is one of the most important applications and helpful. Iodine sublimation can be employed to expose forensic evidence on paper.
2. Sublimation is a process that is used to purify volatile compounds. It is beneficial for organic compounds.
3. Dye-sublimation printers have replaced inkjet printers. Because in the dye sublimation process,  the prints dry faster, and the printouts are ready to use as soon as they come out of the printer.
4. Dye sublimation has wide applications in the textile industry and printing of synthetic fabrics like polyester. This technique is also useful in manufacturing T-shirts, flags, and banners.
5. Dye sublimation is a cost-effective process. Various products such as pens, bags, and coffee mugs are printed with a dye sublimation at less cost. 
6. Space agencies like NASA and ISRO use this method to supply high-quality meals to astronauts in orbit. This method is used when a food product must be stored for an extended period of time.
7. Another application of sublimation is used in the frozen food industry;ze-drying is a popular application.  Frozen water in the substance sublimates from the solid to the gas phase when the surrounding pressure is reduced without forming the liquid phase.
8. It is safe and eco-friendly, and there is no waste produced in this process.

Sublimation Experiment

Experiment Title – Sublimation

Experiment Description – Do you know what happens during the process of sublimation of a sublimate solid? Let’s carry out the sublimation of ammonium chloride to find out.

Aim of Experiment – To study the changes in the state of a sublimate solid on heating.

Material Required – 

• Ammonium chloride (s)
• Watch glass
• Bunsen burner 
• Tripod stand 
• Wire gauze
• China dish 
• Funnel
• Cotton plug
• Spatula

Procedure – 

1. Take powdered sublimable solid (ammonium chloride) in a china dish. 
2. Place the tripod stand along with the wire gauze over the burner.
3. Place the china dish containing ammonium chloride over the wire gauze on the tripod stand. 
4. Put an inverted funnel over the china dish. 
5. Insert a cotton plug into the stem of the funnel. 
6. Heat the china dish slowly with the help of the Bunsen burner.
7. After the entire solid mass has sublimed, stop heating and let the funnel cool down. Remove the funnel and record your observation.

Precautions – 

1. Heat the sample carefully.
2. Take care while plugging the stem of the funnel tightly with cotton.
3. The size of the mouth of the funnel and the china dish should be comparable.
4. Do not remove the funnel when hot.

FAQs on Sublimation