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'''Disodium hydrogen phosphate''' is the ] with the formula Na<sub>2</sub>HPO<sub>4</sub>. It is one of several ] ]s of ]. The salt is known in anhydrous form as well as forms with 2, 7, 8, and 12 ]. All are water-soluble white powders; the anhydrous salt being ].<ref> </ref> '''Disodium hydrogen phosphate''' is the ] with the formula Na<sub>2</sub>HPO<sub>4</sub>. It is one of several ]. The salt is known in anhydrous form as well as forms with 2, 7, 8, and 12 ]. All are water-soluble white powders; the anhydrous salt being ].<ref> </ref>


==Preparation and basic properties== ==Acid-base properties==
⚫ The ] of disodium hydrogen phosphate water solution is between 8.0 and 11.0, meaning it is ]:
⚫ It is prepared in a two-step process by treating ] with phosphoric acid, which precipitates ]:<ref name=Ullmann>Klaus Schrödter, Gerhard Bettermann, Thomas Staffel, Friedrich Wahl, Thomas Klein, Thomas Hofmann "Phosphoric Acid and Phosphates" in ''Ullmann’s Encyclopedia of Industrial Chemistry'' 2008, Wiley-VCH, Weinheim. {{DOI|10.1002/14356007.a19_465.pub3}}</ref>
⚫ :HPO<sub>4</sub><sup>2-</sup> + H<sub>2</sub>O <math>\overrightarrow{\leftarrow}</math> H<sub>2</sub>PO<sub>4</sub><sup>-</sup> + OH<sup>-</sup>

==Production and reactions==
It can be generated by neutralization of ] with ]:
:H<sub>3</sub>PO<sub>4</sub><sup>2-</sup> + 2 NaOH → HNa<sub>2</sub>PO<sub>4</sub> + 2 H<sub>2</sub>O

⚫ Industrially iIt is prepared in a two-step process by treating ] with phosphoric acid, which precipitates ]:<ref name=Ullmann>Klaus Schrödter, Gerhard Bettermann, Thomas Staffel, Friedrich Wahl, Thomas Klein, Thomas Hofmann "Phosphoric Acid and Phosphates" in ''Ullmann’s Encyclopedia of Industrial Chemistry'' 2008, Wiley-VCH, Weinheim. {{DOI|10.1002/14356007.a19_465.pub3}}</ref>
:CaHPO<sub>4</sub> + NaHSO<sub>4</sub> → NaH<sub>2</sub>PO<sub>4</sub> + CaSO<sub>4</sub> :CaHPO<sub>4</sub> + NaHSO<sub>4</sub> → NaH<sub>2</sub>PO<sub>4</sub> + CaSO<sub>4</sub>
In the second step, the resulting solution of monosodium phosphate is partially neutralized: In the second step, the resulting solution of monosodium phosphate is partially neutralized:
:NaH<sub>2</sub>PO<sub>4</sub> + NaOH → HNa<sub>2</sub>PO<sub>4</sub> + H<sub>2</sub>O :NaH<sub>2</sub>PO<sub>4</sub> + NaOH → HNa<sub>2</sub>PO<sub>4</sub> + H<sub>2</sub>O

⚫ The ] of disodium hydrogen phosphate water solution is between 8.0 and 11.0, meaning it is ].
⚫ Heating solid disodium phosphate gives the useful compound ]:
⚫ :2 HNa<sub>2</sub>PO<sub>4</sub> → Na<sub>4</sub>P<sub>2</sub>O<sub>7</sub> + H<sub>2</sub>O


==Uses== ==Uses==
It is used as an in conjunction with ] in many steam-boiler applications. It retards calcium scale formation.anti-scale agent. It is also found in some detergents and cleaning agents.<ref name=Ullmann/> It is used as an in conjunction with ] in foods and water treatment. In foods, it is used to adjust pH. Its presence prevents coagulation in the preparation of condensed milk. Similarly, it is used as an anti-caking additive in powdered products.<ref> </ref> It is used in deserts and puddings, e.g. ] to quicken cook time, and Jell-O Instant Pudding for thickening. In water treatment, It retards ]. It is also found in some detergents and cleaning agents.<ref name=Ullmann/>


⚫ Heating solid disodium phosphate gives the useful compound ]:
Its presence prevents coagulation in the preparation of condensed milk. Similarly, it is used as an anti-caking additive in powdered products.<ref> </ref> It is used in deserts and puddings, e.g. ] to quicken cook time, and Jell-O Instant Pudding for thickening.
:2 HNa<sub>2</sub>PO<sub>4</sub> → Na<sub>4</sub>P<sub>2</sub>O<sub>7</sub> + H<sub>2</sub>O


Monobasic and dibasic sodium phosphate are used as a saline laxative to treat constipation or to clean the bowel before a colonoscopy.<ref>[http://wishardhealth.kramesonline.com/Medications/26,1558</ref> Monobasic and dibasic sodium phosphate are used as a saline laxative to treat constipation or to clean the bowel before a colonoscopy.<ref>[http://wishardhealth.kramesonline.com/Medications/26,1558</ref>

Revision as of 17:31, 4 January 2014

Disodium phosphate
Names
IUPAC name Sodium hydrogen phosphate
Other names Disodium hydrogen orthophosphate
Sodium hydrogen phosphate
Sodium phosphate dibasic
disodium phosphate
Identifiers
CAS Number
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.028.590 Edit this at Wikidata
EC Number
  • 231-448-7
E number E339(ii) (antioxidants, ...)
PubChem CID
RTECS number
  • WC4500000
UNII
CompTox Dashboard (EPA)
InChI
  • InChI=1S/2Na.H3O4P/c;;1-5(2,3)4/h;;(H3,1,2,3,4)/q2*+1;/p-3Key: BNIILDVGGAEEIG-UHFFFAOYSA-K
  • InChI=1/2Na.H3O4P/c;;1-5(2,3)4/h;;(H3,1,2,3,4)/q2*+1;/p-3Key: BNIILDVGGAEEIG-DFZHHIFOAK
SMILES
  • ..P()()=O
Properties
Chemical formula Na2HPO4
Molar mass 141.96 g/mol (anhydrous)
268.07 g/mol (heptahydrate)
Appearance White crystalline solid
Odor odorless
Density 1.7 g/cm
Melting point 250 ºC decomp.
Solubility in water 7.7 g/100 ml (20 ºC)
11.8 g/100 mL (25 °C, heptahydrate)
Acidity (pKa) 12.35
Hazards
Occupational safety and health (OHS/OSH):
Main hazards Irritant
NFPA 704 (fire diamond)
NFPA 704 four-colored diamondHealth 1: Exposure would cause irritation but only minor residual injury. E.g. turpentineFlammability 0: Will not burn. E.g. waterInstability 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1 0 0
Flash point Non-flammable
Related compounds
Other anions sodium phosphite
Other cations Dipotassium phosphate
Diammonium phosphate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C , 100 kPa). ☒N verify (what is  ?) Infobox references
Chemical compound

Disodium hydrogen phosphate is the inorganic compound with the formula Na2HPO4. It is one of several sodium phosphates. The salt is known in anhydrous form as well as forms with 2, 7, 8, and 12 hydrates. All are water-soluble white powders; the anhydrous salt being hygroscopic.

Acid-base properties

The pH of disodium hydrogen phosphate water solution is between 8.0 and 11.0, meaning it is basic:

HPO4 + H2O ← → {\displaystyle {\overrightarrow {\leftarrow }}} H2PO4 + OH

Production and reactions

It can be generated by neutralization of phosphoric acid with sodium hydroxide:

H3PO4 + 2 NaOH → HNa2PO4 + 2 H2O

Industrially iIt is prepared in a two-step process by treating dicalcium phosphate with phosphoric acid, which precipitates calcium sulfate:

CaHPO4 + NaHSO4 → NaH2PO4 + CaSO4

In the second step, the resulting solution of monosodium phosphate is partially neutralized:

NaH2PO4 + NaOH → HNa2PO4 + H2O

Uses

It is used as an in conjunction with trisodium phosphate in foods and water treatment. In foods, it is used to adjust pH. Its presence prevents coagulation in the preparation of condensed milk. Similarly, it is used as an anti-caking additive in powdered products. It is used in deserts and puddings, e.g. Cream of Wheat to quicken cook time, and Jell-O Instant Pudding for thickening. In water treatment, It retards calcium scale formation. It is also found in some detergents and cleaning agents.

Heating solid disodium phosphate gives the useful compound tetrasodium pyrophosphate:

2 HNa2PO4 → Na4P2O7 + H2O

Monobasic and dibasic sodium phosphate are used as a saline laxative to treat constipation or to clean the bowel before a colonoscopy.

References

  1. Physical data (pdf)
  2. ^ Klaus Schrödter, Gerhard Bettermann, Thomas Staffel, Friedrich Wahl, Thomas Klein, Thomas Hofmann "Phosphoric Acid and Phosphates" in Ullmann’s Encyclopedia of Industrial Chemistry 2008, Wiley-VCH, Weinheim. doi:10.1002/14356007.a19_465.pub3
  3. MSDS
  4. [http://wishardhealth.kramesonline.com/Medications/26,1558
Sodium compounds
Inorganic
Halides
Chalcogenides
Pnictogenides
Oxyhalides
Oxychalcogenides
Oxypnictogenides
Others
Organic
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