Phosphoric acid

Phosphoric acid
Names
	IUPAC name Phosphoric acid
	Other names Orthophosphoric acid, hydrogen phosphate
Identifiers
CAS Number	7664-38-2 ;
3D model (JSmol)	Interactive image;
ChEBI	CHEBI:26078 ;
ChEMBL	ChEMBL1187 ;
ChemSpider	979 ;
DrugBank	DB09394;
ECHA InfoCard	100.028.758
EC Number	231-633-2;
E number	E338 (antioxidants, ...)
Gmelin Reference	2000
KEGG	D05467 ;
PubChem CID	1004;
RTECS number	TB6300000;
UNII	E4GA8884NN ;
UN number	1805
CompTox Dashboard (EPA)	DTXSID5024263 ;
	InChI InChI=1S/H3O4P/c1-5(2,3)4/h(H3,1,2,3,4) Key: NBIIXXVUZAFLBC-UHFFFAOYSA-N ; InChI=1/H3O4P/c1-5(2,3)4/h(H3,1,2,3,4) Key: NBIIXXVUZAFLBC-UHFFFAOYAI;
	SMILES OP(=O)(O)O;
Properties
Chemical formula	H3PO4
Molar mass	97.994 g·mol−1
Appearance	Colorless solid
Odor	Odorless
Density	1.6845 g/cm3 (25 °C, 85%), 1.834 g/cm3 (solid)
Melting point	42.35 °C (108.23 °F; 315.50 K) anhydrous; 29.32 °C (84.78 °F; 302.47 K) hemihydrate
Boiling point	212 °C (414 °F) (only water evaporates);
Solubility in water	392.2 g/(100 g) (−16.3 °C); 369.4 g/(100 mL) (0.5 °C); 446 g/(100 mL) (15 °C); 548 g/(100 mL) (20 °C);
Solubility	Soluble in ethanol
log P	−2.15
Vapor pressure	0.03 mmHg (20 °C)
Conjugate base	Dihydrogen phosphate
Magnetic susceptibility (χ)	−43.8·10−6 cm3/mol
Refractive index (nD)	1.3420 (8.8% w/w aq. soln.); 1.4320 (85% aq. soln) 25 °C;
Viscosity	2.4–9.4 cP (85% aq. soln.) ; 147 cP (100%)
Structure
Crystal structure	Monoclinic
Molecular shape	Tetrahedral
Thermochemistry
Heat capacity (C)	145.0 J/(mol⋅K)
Std molar; entropy (S⦵298)	150.8 J/(mol⋅K)
Std enthalpy of; formation (ΔfH⦵298)	−1271.7 kJ/mol
Gibbs free energy (ΔfG⦵)	−1123.6 kJ/mol
Hazards
	GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H290, H314
Precautionary statements	P280, P305+P351+P338, P310
NFPA 704 (fire diamond)	3 0 0
Flash point	Non-flammable
	Lethal dose or concentration (LD, LC):
LD50 (median dose)	1530 mg/kg (rat, oral)
	NIOSH (US health exposure limits):
PEL (Permissible)	TWA 1 mg/m3
REL (Recommended)	TWA 1 mg/m3 ST 3 mg/m3
IDLH (Immediate danger)	1000 mg/m3
Safety data sheet (SDS)	ICSC 1008
Related compounds
Related phosphorus oxoacids	Hypophosphorous acid; Phosphorous acid; Pyrophosphoric acid; Triphosphoric acid; Peroxomonophosphoric acid; Peroxodiphosphoric acid;
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Phosphoric acid (orthophosphoric acid, monophosphoric acid or phosphoric(V) acid) is a colorless, odorless phosphorus-containing solid, and inorganic compound with the chemical formula H₃P O₄. It is commonly encountered as an 85% aqueous solution, which is a colourless, odourless, and non-volatile syrupy liquid. It is a major industrial chemical, being a component of many fertilizers.

The compound is an acid. Removal of all three H⁺ ions gives the phosphate ion PO3−4. Removal of one or two protons gives dihydrogen phosphate ion H₂PO−4, and the hydrogen phosphate ion HPO2−4, respectively. Phosphoric acid forms esters, called organophosphates.^[17]

The name "orthophosphoric acid" can be used to distinguish this specific acid from other "phosphoric acids", such as pyrophosphoric acid. Nevertheless, the term "phosphoric acid" often means this specific compound; and that is the current IUPAC nomenclature.

^ Christensen, J. H.; Reed, R. B. (1955). "Design and Analysis Data—Density of Aqueous Solutions of Phosphoric Acid Measurements at 25 °C". Ind. Eng. Chem. 47 (6): 1277–1280. doi:10.1021/ie50546a061.
^ "CAMEO Chemicals Datasheet – Phosphoric Acid". Archived from the original on 15 August 2019. Retrieved 15 August 2019.
^ "Phosphoric acid". www.chemspider.com. Archived from the original on 12 March 2020. Retrieved 3 March 2020.
^ Brown, Earl H.; Whitt, Carlton D. (1952). "Vapor Pressure of Phosphoric Acids". Industrial & Engineering Chemistry. 44 (3): 615–618. doi:10.1021/ie50507a050.
^ Seidell, Atherton; Linke, William F. (1952). Solubilities of Inorganic and Organic Compounds. Van Nostrand. Archived from the original on 11 March 2020. Retrieved 2 June 2014.
^ Haynes, p. 4.80
^ "phosphoric acid_msds". Archived from the original on 4 July 2017. Retrieved 2 May 2018.
^ ^a ^b ^c ^d NIOSH Pocket Guide to Chemical Hazards. "#0506". National Institute for Occupational Safety and Health (NIOSH).
^ Haynes, p. 5.92
^ Haynes, p. 4.134
^ Edwards, O. W.; Dunn, R. L.; Hatfield, J. D. (1964). "Refractive Index of Phosphoric Acid Solutions at 25 C.". J. Chem. Eng. Data. 9 (4): 508–509. doi:10.1021/je60023a010.
^ Greenwood, N. N.; Thompson, A. (1959). "701. The mechanism of electrical conduction in fused phosphoric and trideuterophosphoric acids". Journal of the Chemical Society (Resumed): 3485. doi:10.1039/JR9590003485.
^ Cite error: The named reference Ross was invoked but never defined (see the help page).
^ Haynes, p. 5.13
^ ^a ^b ^c Sigma-Aldrich Co., Phosphoric acid.
^ "Phosphoric acid". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
^ Westheimer, F.H. (6 June 1987). "Why nature chose phosphates". Science. 235 (4793): 1173–1178 (see pp. 1175–1176). Bibcode:1987Sci...235.1173W. CiteSeerX 10.1.1.462.3441. doi:10.1126/science.2434996. PMID 2434996.

[Density_85%-1] Christensen, J. H.; Reed, R. B. (1955). "Design and Analysis Data—Density of Aqueous Solutions of Phosphoric Acid Measurements at 25 °C". Ind. Eng. Chem. 47 (6): 1277–1280. doi:10.1021/ie50546a061.

[Density_solid-2] "CAMEO Chemicals Datasheet – Phosphoric Acid". Archived from the original on 15 August 2019. Retrieved 15 August 2019.

[chemspider-3] "Phosphoric acid". www.chemspider.com. Archived from the original on 12 March 2020. Retrieved 3 March 2020.

[4] Brown, Earl H.; Whitt, Carlton D. (1952). "Vapor Pressure of Phosphoric Acids". Industrial & Engineering Chemistry. 44 (3): 615–618. doi:10.1021/ie50507a050.

[sioc-5] Seidell, Atherton; Linke, William F. (1952). Solubilities of Inorganic and Organic Compounds. Van Nostrand. Archived from the original on 11 March 2020. Retrieved 2 June 2014.

[crc-6] Haynes, p. 4.80

[chemsrc-7] "phosphoric acid_msds". Archived from the original on 4 July 2017. Retrieved 2 May 2018.

[PGCH-8] NIOSH Pocket Guide to Chemical Hazards. "#0506". National Institute for Occupational Safety and Health (NIOSH).

[9] Haynes, p. 5.92

[10] Haynes, p. 4.134

[Refractive_Index-11] Edwards, O. W.; Dunn, R. L.; Hatfield, J. D. (1964). "Refractive Index of Phosphoric Acid Solutions at 25 C.". J. Chem. Eng. Data. 9 (4): 508–509. doi:10.1021/je60023a010.

[Greenwood-12] Greenwood, N. N.; Thompson, A. (1959). "701. The mechanism of electrical conduction in fused phosphoric and trideuterophosphoric acids". Journal of the Chemical Society (Resumed): 3485. doi:10.1039/JR9590003485.

[Ross-13] Cite error: The named reference Ross was invoked but never defined (see the help page).

[14] Haynes, p. 5.13

[sigma-15] Sigma-Aldrich Co., Phosphoric acid.

[16] "Phosphoric acid". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).

[Westheimer-17] Westheimer, F.H. (6 June 1987). "Why nature chose phosphates". Science. 235 (4793): 1173–1178 (see pp. 1175–1176). Bibcode:1987Sci...235.1173W. CiteSeerX 10.1.1.462.3441. doi:10.1126/science.2434996. PMID 2434996.

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