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No simple silicic acid has ever been identified, since these species are primarily of theoretical interest. Depending on the number of silicon atoms present, there are mono- and polysilicic (di-, tri-, tetrasilicic, etc.) acids. Well defined silicic acids have not been obtained in a form that has been characterized by X-ray crystallography.
CAS number C 10 H 16 N 2 O 8: Ethylenediaminetetraacetic acid (EDTA) 6381–92–6 C 12 H 22 O 11: sucrose: 57–50–1 C 18 H 29 O 3 S: sodium dodecyl benzenesulfonate: 2155–30–0 C 20 H 25 N 30: Lysergic acid diethylamide (LSD) 50–37–3 C 123 H 193 N 35 O 37: Common serum albumin (macromolecule) 9048–49–1 Ca(AlH 4) 2: calcium ...
2009 silicic acid concentration in the upper pelagic zone. [19] Dissolved silica (DSi) is a term used in the field of oceanography to describe the form of water-soluble silica, which is assumed to be Si(OH) 4 (orthosilicic acid) or its conjugate bases (orthosilicate anions) such as − O−Si(OH) 3 and (− O−) 2 Si(OH) 2.
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
For example, the commercially available sodium silicate pentahydrate Na 2 SiO 3 ·5H 2 O is formulated as Na 2 SiO 2 (OH) 2 ·4H 2 O, and the nonahydrate Na 2 SiO 3 ·9H 2 O is formulated as Na 2 SiO 2 (OH) 2 ·8H 2 O. [5] The pentahydrate and nonahydrate forms have their own CAS Numbers, 10213-79-3 and 13517-24-3 respectively.
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 .
In acidic solutions, the silicate ions react with hydrogen ions to form silicic acids, which tend to decompose into hydrated silicon dioxide gel. [citation needed] Heated to drive off the water, the result is a hard translucent substance called silica gel, widely used as a desiccant. It can withstand temperatures up to 1100 °C. [citation needed]
W-silica is an unstable low-density form involving SiO tetrahedra sharing opposite edges instead of corners, forming parallel chains similarly to silicon disulfide (SiS 2) and silicon diselenide (SiSe 2): it quickly returns to forming amorphous silica with heat or traces of water. [14] Condensed polysilicic acid. Silica is rather inert chemically.