Dihydrogen phosphate

Dihydrogen phosphate
Names
IUPAC name
Dihydrogenphosphate
Systematic IUPAC name
Phosphoric acid, ion(1−)
Other names
Phosphoric acid, ion(1−) Dehydrophosphoric acid (1−)
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
DrugBank
1999
  • InChI=1S/H3O4P/c1-5(2,3)4/h(H3,1,2,3,4)/p-1
    Key: NBIIXXVUZAFLBC-UHFFFAOYSA-M
  • OP(=O)(O)[O-]
Properties
H2O4P−1
Molar mass 96.986 g·mol−1
Conjugate acid Phosphoric Acid
Related compounds
Related compounds
 Phosphate, Monohydrogen phosphate
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Dihydrogen phosphate is an inorganic ion with the formula [H2PO4]−. Phosphates occur widely in natural systems.[1] Perhaps the most common salt of dihydrogen phosphate is sodium dihydrogen phosphate. It is used in animal feed, fertilizer, buffer (in food), and treating metal surfaces.[2]

Structure

The dihydrogen phosphate anion consists of a central phosphorus atom bonded two oxides and two hydroxy groups in a tetrahedral arrangement.[3]

Acid-base equilibria

Dihydrogen phosphate can be both a hydrogen donor and acceptor.

Equilibrium Disassociation constant, pKa[4]
H3PO4 ⇌ H
2PO−
4 + H+		 pKa1 = 2.14[a]
H
2PO−
4 ⇌ HPO2−
4 + H+		 pKa2 = 7.20
HPO2−
4 ⇌ PO3−
4 + H+		 pKa3 = 12.37

Examples

  • Ammonium dihydrogen phosphate ((NH4)(H2PO4))
  • Monocalcium phosphate (Ca(H2PO4)2)

Safety

Many foods including milk, eggs, poultry, and nuts contain these sodium phosphates.[1]

Notes

  1. ↑ Values are at 25 °C and 0 ionic strength.

References

  1. 1 2 Tech, Noah. "Sodium Phosphates: From Food to Pharmacology | Noah Technologies". Retrieved 2021-03-23.
  2. ↑ Havelange, Sébastien; Lierde, Nicolas; Germeau, Alain; Martins, Emmanuel; Theys, Tibaut; Sonveaux, Marc; Toussaint, Claudia; Schrödter, Klaus; Bettermann, Gerhard; Staffel, Thomas; Wahl, Friedrich; Klein, Thomas; Hofmann, Thomas (2022). "Phosphoric Acid and Phosphates". Ullmann's Encyclopedia of Industrial Chemistry. pp. 1–55. doi:10.1002/14356007.a19_465.pub4. ISBN 978-3-527-30385-4.
  3. ↑ PubChem. "Dihydrogen phosphate". pubchem.ncbi.nlm.nih.gov. Retrieved 2021-03-23.
  4. ↑ Powell, Kipton J.; Brown, Paul L.; Byrne, Robert H.; Gajda, Tamás; Hefter, Glenn; Sjöberg, Staffan; Wanner, Hans (2005). "Chemical speciation of environmentally significant heavy metals with inorganic ligands. Part 1: The Hg2+, Cl−, OH−, CO2−
    3    , SO2−
    4    , and PO3−
    4     aqueous systems"    . Pure Appl. Chem. 77 (4): 739–800. doi:10.1351/pac200577040739.
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