silica gel

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silica gel,

chemical compound. It is a colloidal form of silicasilica
or silicon dioxide,
chemical compound, SiO2. It is insoluble in water, slightly soluble in alkalies, and soluble in dilute hydrofluoric acid. Pure silica is colorless to white.
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, and usually resembles coarse white sand. It may be prepared by partial dehydration of metasilicic acid, H2SiO3. Because it has many tiny pores, it has great adsorptive power. It is used as a drying agent, as a catalyst or catalyst carrier, and in purifying various substances. Silica aerogelaerogel,
any of a group of extremely light and porous solid materials; the lightest is less than four times as dense as dry air. Aerogels are produced from certain gels (see colloid) by heating the gel under pressure, which causes the liquid in the gel to become supercritical
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 is fully dehydrated silica gel; it is very porous and is often used in insulation, e.g., for refrigerators.
The Columbia Electronic Encyclopedia™ Copyright © 2013, Columbia University Press. Licensed from Columbia University Press. All rights reserved. www.cc.columbia.edu/cu/cup/
The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Silica Gel

 

the desiccated gel of polysilicic acid; a solid hy-drophilic sorbent. By composition, silica gel is silicon dioxide (silica), and by structure, a highly porous body composed of extremely minute, accreted spherical particles.

In the manufacture of silica gel, a solution of sodium or potassium silicate (water glass) is first acted upon by hydrochloric or sulfuric acid. The congealed product is then broken into pieces, rinsed with water, dried, ground, fractionated, and roasted to remove all moisture. Commercial silica gel is available in grains or globular granules 5-7 to 10-2 mm in size. Various brands of silica gel have a mean effective pore diameter of 20–150 angstroms and a specific surface of 102-103 m2/g.

Silica gel is used to absorb water vapor and the vapors of organic solvents. It is also used for the absorptive purification of nonpolar liquids and for the separation of alcohols, amino acids, vitamins, and antibiotics in gas and liquid chromatography. Macroporous silica gel serves as a catalyst base.

REFERENCE

Kol’tsov, S. I., and V. B. Aleskovskii. Silikagel’, ego stroenie i khimiches-kiesvoistva. Leningrad, 1963.
The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.

silica gel

[′sil·ə·kə ¦jel]
(inorganic chemistry)
A colloidal, highly absorbent silica used as a dehumidifying and dehydrating agent, as a catalyst carrier, and sometimes as a catalyst.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.

silica gel, synthetic silica

A form of silica which adsorbs moisture readily; used as a drying agent.
McGraw-Hill Dictionary of Architecture and Construction. Copyright © 2003 by McGraw-Hill Companies, Inc.

silica gel

A form of porous silica used as a desiccant. It is used as a drying or moisture-absorbing agent in packing and sometimes in avionics themselves.
An Illustrated Dictionary of Aviation Copyright © 2005 by The McGraw-Hill Companies, Inc. All rights reserved

silica gel

An absorbent form of silicon dioxide often wrapped in small packets that is shipped with equipment to absorb moisture. Silica gel packets are desiccants.

Don't Throw Them Away
Silica gel packets can be used to remove odors in a gym bag. Stored in a box of photos, they can prevent them from sticking to each other, and they can extend the life of razors by eliminating moisture. A wet phone can be dried out if placed in a jar filled with the gel bags. See silicon dioxide.


Silica Gel Packets
These commonly found desiccants are small beads of silica gel inside paper packets.
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