Silicic acid is a
chemical compound. It is a
silanol. 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 (H
2SiO
3),
orthosilicic acid (H
4SiO
4, pK
a1=9.84, pK
a2=13.2 at 25 °C),
disilicic acid (H
2Si
2O
5), and
pyrosilicic acid (H
6Si
2O
7); however in the solid state these probably condense to form polymeric silicic acids of complex structure.