Silicic acid

In chemistry, a silicic acid (/sɪˈlɪsɪk/) is any chemical compound containing the element silicon attached to oxide (=O) and hydroxyl (−OH) groups, with the general formula [H_2xSiO_x+2]_n or, equivalently, [SiO_x(OH)_4−2x]_n.^[1]^[2] Orthosilicic acid is a representative example. Silicic acids are rarely observed in isolation, but are thought to exist in aqueous solutions, including seawater, and play a role in biomineralization.^[3] They are typically colorless weak acids that are sparingly soluble in water. Like the silicate anions, which are their better known conjugate bases, silicic acids are proposed to be oligomeric or polymeric. 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.

^ Greenwood, N. N.; Earnshaw, A. (2012). Chemistry of the Elements. Elsevier Science. p. 346. ISBN 978-0-08-050109-3. Retrieved July 27, 2022.
^ Iler, R. K. (1979). The Chemistry of Silica. New York: Wiley. ISBN 0-471-02404-X.
^ Frank Wigglesworth Clarke (1914). "The Silicic Acids" (PDF). The Constitution of the Natural Silicates. pp. 10–19.

[Greenwood-1] Greenwood, N. N.; Earnshaw, A. (2012). Chemistry of the Elements. Elsevier Science. p. 346. ISBN 978-0-08-050109-3. Retrieved July 27, 2022.

[2] Iler, R. K. (1979). The Chemistry of Silica. New York: Wiley. ISBN 0-471-02404-X.

[3] Frank Wigglesworth Clarke (1914). "The Silicic Acids" (PDF). The Constitution of the Natural Silicates. pp. 10–19.

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