Sodium hexametaphosphate
 | |
| Names | |
|---|---|
| Other names
Calgon S Glassy sodium | |
| Identifiers | |
| 3D model (Jmol) | Interactive image |
| ChemSpider | 23340  |
| ECHA InfoCard | 100.030.299 |
| EC Number | 233-343-1 |
| MeSH | sodium+polymetaphosphate |
| PubChem | 24968 |
| |
| |
| Properties | |
| Na 6P 6O 18 | |
| Molar mass | 611.7704 g mol−1 |
| Appearance | White crystals |
| Odor | odorless |
| Density | 2.484 g/cm3 |
| Melting point | 628 °C (1,162 °F; 901 K) |
| Boiling point | 1,500 °C (2,730 °F; 1,770 K) |
| soluble | |
| Solubility | insoluble in organic solvents |
| Refractive index (nD) |
1.482 |
| Hazards | |
| Main hazards | Irritant |
| Safety data sheet | hazard.com |
| S-phrases | S24/25 |
| Lethal dose or concentration (LD, LC): | |
| LD50 (median dose) |
3.053 g kg−1 |
| Related compounds | |
| Other anions |
Trisodium phosphate Tetrasodium pyrophosphate Pentasodium triphosphate |
| Related compounds |
Sodium trimetaphosphate |
| Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
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| 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.
Uses
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.
A significant use for sodium hexametaphosphate is as a deflocculant in the production of clay-based ceramic particles.[3][4][5][6] It is also used as a dispersing agent to break down clay and other soil types.[7]
It is used as an active ingredient in toothpastes as an anti-staining and tartar prevention ingredient.[8]
Food additive
Artificial maple syrup, canned milk, cheese powders and dips, imitation cheese, whipped topping, packaged egg whites, roast beef, fish fillets, fruit jelly, frozen desserts, salad dressing, herring, breakfast cereal, ice cream, beer, and bottled beverages, among other foods, can contain sodium hexametaphosphate. [9][10][11]
Preparation
SHMP is prepared by heating monosodium orthophosphate to generate sodium acid pyrophosphate:
- 2 NaH2PO4 → Na2H2P2O7 + H2O
Subsequently, the pyrophosphate is heated to give the corresponding sodium hexametaphosphate:
- 3 Na2H2P2O7 → (NaPO3)6 + 3 H2O
followed by rapid cooling.
Reactions
SHMP hydrolyzes in aqueous solution, particularly under acidic conditions, to sodium trimetaphosphate and sodium orthophosphate.[12]
References
- ↑ Merck Index, 12th Edition, Sodium polymetaphosphate, 8814
- ↑ Van Wazer, John R. Phosphorus and its compounds. New York : Interscience Publishers (1958)
- ↑ The Role Of Sodium Hexametaphosphate In The Dissolution Process Of Kaolinite And KaolinF. Andreola; E.Castellini; T.Manfredini; M.Romagnoli. Journal Of The European Ceramic Society, Volume 24, Number 7, June 2004.
- ↑ Impact Of Dispersants On The Mechanical Strength Development Of Alumina-Spinel Self-Flowing Refractory Castables. Sasan Otroj, Mohammad Reza Nilforushan, Arash Daghighi, Reza Marzban. Ceramics – Silikáty 54 (3) 284–289 (2010)
- ↑ Effect Of Adding Sodium Hexametaphosphate Liquefier On Basic Properties Of Calcium Phosphate Cements. S. Hesaraki; A. Zamanian; F. Moztarzadeh. Journal of Biomedical Materials Research Part A. Vol. 88A, No. 2, 2009
- ↑ Study Of Clay’s Mineralogy Effect On Rheological Behavior Of Ceramic Suspensions Using An Experimental Design. Afef Jmal Ayadi; Julien Soro; Amel Kamoun; Samir Baklouti. International Journal of Recent Research and Applied Studies 14 (2). February 2013.
- ↑ ASTM D422 – 63(2007) Standard Test Method for Particle-Size Analysis of Soils.
- ↑ Crest Pro-Health Frequently Asked Questions
- ↑ http://www.befoodsmart.com/ingredients/sodium-hexametaphosphate.php
- ↑ http://www.fda.gov/food/ingredientspackaginglabeling/foodadditivesingredients/ucm091048.htm
- ↑ http://www.accessdata.fda.gov/scripts/cdrh/cfdocs/cfcfr/cfrsearch.cfm?fr=173.310
- ↑ Van Wazer, John (1958). Phosphorus and its Compounds. New York: Interscience Publishers. Retrieved 7 April 2015.