Have you ever wondered how dry ice produces fog or how naphthalene balls disappear over time? These are examples of a process called Sublimation, which is the transition of a substance from the solid to the gas state without passing through the liquid form. In this article, I will explain what Sublimation is, how it works, and why it is essential for various applications.
What Sublimation is?
Sublimation is a type of phase change in the physical state of matter. Phase changes occur when a substance absorbs or releases heat, affecting molecular motion and intermolecular forces. For example, when ice melts, it absorbs heat, and the molecules gain enough energy to overcome the attractive forces that hold them together in a solid structure. The ice becomes liquid water with more freedom of movement and less order.
However, Sublimation is different from other phase changes because it skips the liquid phase altogether. Instead of melting, the solid substance directly vaporizes into a gas. This happens when the vapor pressure of the concrete is higher than the surrounding pressure of the same meaning. Vapor pressure is the pressure exerted by the molecules of a substance in the gas phase, and it depends on the temperature and the strength of the intermolecular forces. The stronger the intermolecular forces, the lower the vapor pressure and the higher the temperature needed for Sublimation.
How does Sublimation work?
Sublimation requires a lot of energy because it involves breaking all the solid’s intermolecular forces and increasing the gas’s molecular motion. The amount of energy needed for Sublimation is called the enthalpy of Sublimation, and it can be calculated by adding the enthalpy of fusion (the power needed to melt a solid) and the enthalpy of vaporization (the energy required to vaporize a liquid). For more about Heat of sublimation.
Sublimation can be represented by the following equation:
To illustrate how Sublimation works, let’s take the example of dry ice, the solid form of carbon dioxide. Dry ice sublimes at room temperature and normal atmospheric pressure because its vapor pressure is much higher than the pressure of carbon dioxide in the air. When dry ice is exposed to air, it absorbs heat from the surroundings, and the molecules gain enough energy to escape from the solid lattice. The dry ice becomes carbon dioxide gas, which appears as fog or smoke.
The following diagram shows the Sublimation of dry ice using mermaid syntax:
Molecular Explanation of Sublimation
Sublimation is the phase transition of a substance to the gas phase without passing through the liquid phase. This happens when the molecules of the stable have enough kinetic energy to overcome the intermolecular forces that hold them together in a fixed structure. The molecules escape from the surface of the concrete and enter the gas phase, where they have more freedom of movement and less order.
Sublimation is an endothermic process which absorbs heat from the surroundings. The amount of heat required for Sublimation is equal to the sum of the heat of fusion and the heat of vaporization of the substance.
Why is Sublimation necessary?
Sublimation is not only a fascinating phenomenon but also useful for various applications. Here are some examples of how Sublimation is used in different fields:
- In the textile industry, Sublimation is used for printing designs on fabrics. A special ink is applied to a paper and pressed onto the material under high temperature and pressure. The ink sublimes and transfers to the fabric, creating a permanent and vibrant image.
- In the food industry, freeze-drying is a method of preserving food by Sublimation. The food is frozen and placed in a vacuum chamber, where the water sublimes from the solid to the gas phase. This removes the moisture from the food, preventing microbial growth and spoilage. Freeze-dried food retains its original shape, color, flavor, and nutrients and can be rehydrated.
- In forensic science, the Sublimation of iodine can reveal latent fingerprints on paper. Iodine crystals are heated in a closed container, producing iodine vapor that reacts with the oils and fats in the fingerprints. The fingerprints become visible as brown or purple marks on the paper, which can be photographed or lifted with tape.
- In the chemical industry, Sublimation is used to purify volatile compounds with low melting points. For example, naphthalene, camphor, and iodine can be filtered by Sublimation, as they sublime easily and leave behind impurities in the solid residue.
These are just examples of how Sublimation is used in various applications. Sublimation is a remarkable process demonstrating matter’s diversity, complexity, and behavior.
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I hope you enjoyed reading this article and learned something new about Sublimation. If you have any questions or comments, please share them below. Thank you for your attention.
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