Sodium hexametaphosphate

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Sodium hexametaphosphate[1]
Identifiers
CAS number10124-56-8 YesY
PubChem24968
ChemSpider23340 N
EC number233-343-1
MeSHsodium+polymetaphosphate
Jmol-3D imagesImage 1
Properties
Molecular formulaNa
6
P
6
O
18
Molar mass611.7704 g mol−1
AppearanceWhite crystals
Odorodorless
Density2.484 g/cm3
Melting point

628 °C, 901 K, 1162 °F

Boiling point

1500 °C, 1773 K, 2732 °F

Solubility in watersoluble
Solubilityinsoluble in organic solvents
Refractive index (nD)1.482
Hazards
MSDShazard.com
S-phrasesS24/25
Main hazardsIrritant
LD503.053 g kg−1
Related compounds
Other anionsTrisodium phosphate
Tetrasodium pyrophosphate
Pentasodium triphosphate
Related compoundsSodium trimetaphosphate
 N (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references
 
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Sodium hexametaphosphate[1]
Identifiers
CAS number10124-56-8 YesY
PubChem24968
ChemSpider23340 N
EC number233-343-1
MeSHsodium+polymetaphosphate
Jmol-3D imagesImage 1
Properties
Molecular formulaNa
6
P
6
O
18
Molar mass611.7704 g mol−1
AppearanceWhite crystals
Odorodorless
Density2.484 g/cm3
Melting point

628 °C, 901 K, 1162 °F

Boiling point

1500 °C, 1773 K, 2732 °F

Solubility in watersoluble
Solubilityinsoluble in organic solvents
Refractive index (nD)1.482
Hazards
MSDShazard.com
S-phrasesS24/25
Main hazardsIrritant
LD503.053 g kg−1
Related compounds
Other anionsTrisodium phosphate
Tetrasodium pyrophosphate
Pentasodium triphosphate
Related compoundsSodium trimetaphosphate
 N (verify) (what is: YesY/N?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Sodium hexametaphosphate (SHMP) is a hexamer of composition (NaPO3)6.[2] Sodium hexametaphosphate of commerce is typically a mixture of polymeric metaphosphates, of which the hexamer is one, and is usually the compound referred to by this name. It is more correctly termed sodium polymetaphosphate. It is prepared by melting monosodium orthophosphate, followed by rapid cooling. SHMP hydrolyzes in aqueous solution, particularly under acidic conditions, to sodium trimetaphosphate and sodium orthophosphate.

Uses[edit]

SHMP is used as a sequestrant and has applications within a wide variety of industries, including as a food additive in which it is used under the E number E452i. Sodium carbonate is sometimes added to SHMP to raise the pH to 8.0-8.6, which produces a number of SHMP products used for water softening and detergents. Also used as a dispersing agent to break down clay and other soil types.

One of the lesser-known uses for sodium hexametaphosphate is as a deflocculant in the making of terra sigillata, a ceramic technique using a fine particled slip. The sodium hexametaphosphate or another deflocculant allows the clay particles of an ordinary slip to remain suspended for an extended period of time; after 24hrs or more, the slip separates into layers with the larger particles at the bottom, and the finest particles can be siphoned off and applied to a green ware ceramic surface. It is also used as a deflocculant or dispersant for the ASTM D422 - 63(2007) Standard Test Method for Particle-Size Analysis of Soils.

It can be prepared from Na2HPO4 and NaH2PO4.[citation needed]

It is currently used as an active ingredient in Crest Pro-Health as a claimed anti-staining and tartar prevention ingredient.[3]

References[edit]

  1. ^ Merck Index, 12th Edition, Sodium polymetaphosphate, 8814
  2. ^ Van Wazer, John R. Phosphorus and its compounds. New York : Interscience Publishers (1958)
  3. ^ http://www.crestprohealth.com/pro-health-faq/

External links[edit]