Sodium fluorosilicate

Sodium fluorosilicate

Unit cell of sodium hexafluoridosilicate
Names
Preferred IUPAC name Sodium fluorosilicate
Systematic IUPAC name Sodium hexafluoridosilicate(2–) [1]
Other names Disodium hexafluorosilicate/sodium fluosilicate/sodium silicofluoride
Identifiers
CAS Number	16893-85-9 Y
3D model (JSmol)	Interactive image
ChemSpider	26165 Y
ECHA InfoCard	100.037.198
EC Number	240-934-8
PubChem CID	28127
RTECS number	VV8410000
UNII	806AV2E065 Y
UN number	2674
CompTox Dashboard (EPA)	DTXSID9036933
InChI InChI=1S/F6Si.2Na/c1-7(2,3,4,5)6;;/q-2;2*+1 Key: TWGUZEUZLCYTCG-UHFFFAOYSA-N
SMILES [Na+].[Na+].F[Si--](F)(F)(F)(F)F
Properties
Chemical formula	Na2[SiF6]
Molar mass	188 g/mol
Appearance	white granular powder
Odor	odorless
Density	2.7 g/cm3
Solubility in water	0.64 g/100 mL (20 °C) 1.27 g/100 mL (50 °C) 2.45 g/100 mL (100 °C)
Solubility	insoluble in alcohol
Refractive index (nD)	1.312
Structure[2]
Crystal structure	trigonal
Space group	P321
Lattice constant	a = 8.859, c = 5.038
Formula units (Z)	4
Hazards
NFPA 704 (fire diamond)	2 0 0
Lethal dose or concentration (LD, LC):
LDLo (lowest published)	70 mg/kg (mouse, oral) 125 mg/kg (rabbit, oral)[3]
Related compounds
Other cations	Ammonium hexafluorosilicate Fluorosilicic acid
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Sodium fluorosilicate is a compound with the chemical formula Na₂[SiF₆]. Unlike other sodium salts, it has a low solubility in water.

Natural occurrence

Sodium hexafluorosilicate occurs naturally as the rare mineral malladrite found within some volcanic fumaroles.^[4]

Manufacturing

Sodium fluorosilicate is made by neutralizing fluorosilicic acid with sodium chloride or sodium sulfate.

H₂[SiF₆] + 2 NaCl → Na₂[SiF₆] + 2 HCl

Possible application

It is used in some countries as additives for water fluoridation, opal glass raw material, ore refining, or other fluoride chemical (like sodium fluoride, magnesium silicofluoride, cryolite, aluminum fluoride) production.^[5]

See also

• Fluorosilicic acid
• Ammonium fluorosilicate

References