[Chemistry Class Notes] on “Silica Gel- Properties, Uses, Types, Effects, and FAQS” Pdf for Exam

Silica gel is a form of silicon dioxide that is porous as well as amorphous. It consists of a framework of tridimensional and also irregular geometry of alternating silicon (Si) and oxygen (O) atoms with a scale of nanometer voids and pores. The voids of the silica gel structure may contain either liquid or gas, vaccum. 

Manufacturers often put little packets of the gel as it is a desiccant or drying agent that helps to keep moisture from damaging certain food products and also commercial products. Silica gel is usually prepared by the process of acidification of a solution of a silicate (water glass).

Properties of Silica Gel

Some of the properties of silica gel are given below.

  • The Molecular Weight of silica gel is 60.09 g/mol.

  • Its appearance is translucent solid.

  • The melting point of silica gel is 1200 °C.

  • The specific surface area of silica gel is 500-950 m2/g.

  • Its electrical resistivity is 1015 Ω-cm.

  • The chemical name for the silica gel is silicon dioxide and the formula is SiO2. The molecule of silicon dioxide consists of two-atom of oxygen and one atom of silicon. Oxygen and silicon are the most abundant materials. The crust of the earth is 59 percent silica.

Uses of Silica Gel

Some of the major uses of silica gel are mentioned below.

A desiccant is a hygroscopic material used for maintaining dryness. For manufacturers, the purpose of silica gel is to be used as a desiccant. Silica gel also serves to keep the relative humidity inside a system of satellite transmission waveguide as low as possible. In compressed air systems of any industry, silica gel is also used to dry the air. Where a bed of silica gel beads is made for the air from the compressor discharge to flow through it. The silica gel beads are used for adsorbing the amount of moisture present in the air and preventing it from damaging at the point of use of the compressed air due to condensation. A similar kind of system is used for drying the compressed air on railway locomotives.

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Silica gel has water absorption properties because of this property it is used in domestic water filters. Some minerals that are dissolved in water can be absorbed by the surface structure of silica gel. Because of the lack of regulations for products of the filtrations of domestic water, no studies give validation to the manufacturer claims regarding the effectiveness of the filtration system of sorbent silica gel.

The silica gel changes its colour slowly whenever it is doped with an indicator of moisture as it transitions from the anhydrous state which is a dry state to the hydrated state that is a wet state. 

Silica gel in chemistry is applied in chromatography as a stationary phase. This gel is also applied to glass, plastic sheets and aluminium for thin-layer chromatography. Silica gel is also bound to chelating covalently. These materials possess the ability to remove the metal ions selectively from aqueous solutions. Chelating groups are able to make bonds (covalent bonds) to polyamines. This can also be combined with alkali metals and it forms an M-SG reducing agent. Silicon dioxide is not expected to biodegrade in soil and water.

Silica gel side effects

Some of the side effects of silica gel if eaten in excessive amounts are listed below. Now see what happens if you eat silica gel.

  • If someone has eaten silica gel in large quantities it can cause dehydration. This may create irritation in the throat and nose.

  • Silica gel is non-toxic material but sometimes it is a choking hazard for young children. Hence it should be put away from the reach of children.

  • It can cause stomach pains, vomiting, constipation, and nausea. Medical attention should be taken if vomiting is repeatedly occurring or can’t keep food down, experiencing stomach pains, having an intestinal obstruction etc.

  • If silica gel gets into our eyes, it might cause irritation. As a result, we must first rinse our eyes with lukewarm water.

  • Dust of crystalline silica is a cause of disease silicosis which is a lung disease.

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Do you know?

  • However this is unique about silica gel in that it is not a gel, nor will it dissolve in most liquids. It has a tendency to absorb water and other liquids instead of dissolving in them. 

  • If you add silica gel in water it will absorb water around up to 40% of its weight in water.

Conclusion

We must have seen silica gel crystals in the new packaging of products as it is put there to absorb moisture. Silica gel desiccant property is widely used by manufacturers. We get all the important information related to silica gel such as what is the use of silica gel and its side effects as well.

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