Chemistry:Monosodium phosphate
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 Phosphorus, P Oxygen, O Hydrogen, H Sodium, Na | |
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| Names | |
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| IUPAC name
Sodium dihydrogen phosphate
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Other names
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| Identifiers | |
3D model (JSmol)
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PubChem CID
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| Properties | |
| NaH 2PO 4 | |
| Molar mass | 119.976 g·mol−1 |
| Appearance | White powder or crystals |
| Density | 2.36 g/cm3 (anhydrous) |
| 59.90 g/(100 mL) (0°C) | |
| Hazards | |
| NFPA 704 (fire diamond) | |
| Flash point | Non-flammable |
| Related compounds | |
Other cations
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Related compounds
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). | |
 verify (what is   ?)
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| Infobox references | |
Monosodium phosphate (MSP), also known as monobasic sodium phosphate and sodium dihydrogen phosphate, is an inorganic compound with the chemical formula NaH
2PO
4. It is a sodium salt of phosphoric acid. It consists of sodium cations (Na+
) and dihydrogen phosphate anions (H
2PO−
4). One of many sodium phosphates, it is a common industrial chemical. The salt exists in an anhydrous form, as well as monohydrate and dihydrate (NaH
2PO
4 · H2O and NaH
2PO
4 · 2H2O respectively).[1]
Production and reactions
The salt is obtained by partial neutralization of phosphoric acid. The pKa of monosodium phosphate is 6.8-7.2 (depending on the physicochemical characteristics during pKa determination).[2]
Heating this salt above 169 °C gives disodium pyrophosphate:
- 2 NaH
2PO
4 → Na
2H
2P
2O
7 + H
2O
When heated at 550 °C, anhydrous trisodium trimetaphosphate is formed:[3]
- 3 NaH
2PO
4 → Na
3P
3O
9 + 3 H
2O
Uses
Phosphates are often used in foods and in water treatment. The pH of such formulations is generally adjusted by mixtures of various sodium phosphates, such as this salt.[1] The sodium chloride equivalent value, or E-Value, is 0.49.[clarification needed] It is soluble in 4.5 parts water.[clarification needed]
Food additive
It is added in animal feed, toothpaste, and evaporated milk. It is used as a thickening agent and emulsifier.
Detection of magnesium
Monosodium phosphate is used to detect the presence of magnesium ions in salts. Formation of a white precipitate on the addition of ammonium chloride, ammonium hydroxide and monosodium phosphate to an aqueous or dilute HCl solution of the salt indicates presence of magnesium ions.
Notes
- ↑ 1.0 1.1 Schrödter, Klaus; Bettermann, Gerhard; Staffel, Thomas; Wahl, Friedrich; Klein, Thomas; Hofmann, Thomas (2008). "Ullmann's Encyclopedia of Industrial Chemistry". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a19_465.pub3.
- ↑ Salaun, F.: "Influence of mineral environment on the buffering capacity of casein micelles" , "Milchwissenschaft", 62(1):3
- ↑ Bell, R. N. (1950). "Sodium Metaphosphates". Inorganic Syntheses. Inorganic Syntheses. 3. pp. 103–106. doi:10.1002/9780470132340.ch26. ISBN 9780470132340.
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