Silicic acid

Silicic acid

Names
IUPAC name Silicic acid
Other names Monosilicic acid Orthosilicic acid
Identifiers
CAS Number	10193-36-9 Y
3D model (Jmol)	Interactive image
ChEBI	CHEBI:26675 Y
ChemSpider	14236 Y
ECHA InfoCard	100.109.340
EC Number	233-477-0
Gmelin Reference	2009
PubChem	14942
UNII	623B93YABH N
InChI InChI=1S/H4O4Si/c1-5(2,3)4/h1-4H Y Key: RMAQACBXLXPBSY-UHFFFAOYSA-N Y InChI=1S/H4O4Si/c1-5(2,3)4/h1-4H Key: RMAQACBXLXPBSY-UHFFFAOYSA-N InChI=1/H4O4Si/c1-5(2,3)4/h1-4H Key: RMAQACBXLXPBSY-UHFFFAOYAS
SMILES O[Si](O)(O)O
Properties
Chemical formula	H4O4Si
Molar mass	96.11 g·mol−1
Acidity (pKa)	9.84, 13.2
Magnetic susceptibility (χ)	−42.6·10−6 cm3/mol
Related compounds
Related compounds	Orthocarbonic acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N  (what is YN ?)
Infobox references

Silicic acid /sɪˈlɪsɪk ˌæsɪd/ is a chemical compound. Silicic acid is the general name for a family of chemical compounds containing the element silicon attached to oxide and hydroxyl groups. This family of compounds have the general formula [SiO_x(OH)_4-2x]_n. Some simple silicic acids have been identified, but only in very dilute aqueous solution, such as metasilicic acid (H₂SiO₃), orthosilicic acid (H₄SiO₄, pK_a1=9.84, pK_a2=13.2 at 25 °C), disilicic acid (H₂Si₂O₅), and pyrosilicic acid (H₆Si₂O₇); however in the solid state these probably condense to form polymeric silicic acids of complex structure.

In general, silicic acid reactions are difficult to control. Partial dehydration to metasilicic acid, for example, is challenging because the reaction typically progresses all the way to silicon dioxide and water.

Like other silanols, silicic acid is a weak acid. It can be deprotonated in solution, the conjugate base silicate is known.

Silicic acid was discovered by Jöns Jacob Berzelius between 1810 and 1836 when studying silicon generated by his experiments. However, he failed to recognise it as distinct from silicon dioxide.