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Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula SiO 2, commonly found in nature as quartz. [5] [6] In many parts of the world, silica is the major constituent of sand. Silica is one of the most complex and abundant families of materials, existing as a compound of several minerals and as a synthetic product.
Liquid silicon dioxide (colloidal silica) is used as a wine and juice fining agent. Absorbent; Colloidal silica is used in concrete densifiers and polished concrete. In manufacturing Quantum dots, small semi-conductors used in various scientific research settings. Reduced porosity and increased protection from alkali-silica reaction (ASR). [2]
Coesite (/ ˈ k oʊ s aɪ t /) [3] is a form of silicon dioxide (Si O 2) that is formed when very high pressure (2–3 gigapascals), and moderately high temperature (700 °C, 1,300 °F), are applied to quartz. Coesite was first synthesized by Loring Coes, Jr., a chemist at the Norton Company, in 1953. [4] [5]
Hydrated silica is a form of silicon dioxide, which has a variable amount of water in the formula. When dissolved in water, it is usually known as silicic acid. It is found in nature as opal [2] (which has been mined as a gemstone for centuries), and in the cell walls of diatoms.
Silica gel is an amorphous and porous form of silicon dioxide (silica), consisting of an irregular tridimensional framework of alternating silicon and oxygen atoms with nanometer-scale voids and pores. The voids may contain water or some other liquids, or may be filled by gas or vacuum.
Oxidation of organosilicon compounds, including siloxanes, gives silicon dioxide. This conversion is illustrated by the combustion of hexamethylcyclotrisiloxane: ((CH 3) 2 SiO) 3 + 12 O 2 → 3 SiO 2 + 6 CO 2 + 9 H 2 O. Strong base degrades siloxane group, often affording siloxide salts: ((CH 3) 3 Si) 2 O + 2 NaOH → 2 (CH 3) 3 SiONa + H 2 O
Silicon is the eighth most common element in the universe by mass, but very rarely occurs in its pure form in the Earth's crust. It is widely distributed throughout space in cosmic dusts, planetoids, and planets as various forms of silicon dioxide (silica) or silicates.
The anhydrous compound can be prepared by fusing silicon dioxide SiO 2 (silica, quartz) with sodium oxide Na 2 O in 1:1 molar ratio. [2] The compound crystallizes from solution as various hydrates, such as pentahydrate Na 2 SiO 3 ·5 H 2 O (CAS 10213-79-3, EC 229-912-9, PubChem 57652358) nonahydrate Na 2 SiO 3 ·9 H 2 O (CAS 13517-24-3, EC 229 ...