Phosphoric Acid

An inorganic compound, H3O4P, 97.994 g/mol. Boiling point 407 °C, melting point 42.4 °C, as published.

verified recordInorganic compound8 measured properties

Identifiers

Molecular formula: H₃O₄P
Molecular weight: 97.994 g/mol
Exact mass: 97.976895 g/mol
IUPAC name: phosphoric acid
SMILES: O=P(O)(O)O
InChI: InChI=1S/H3O4P/c1-5(2,3)4/h(H3,1,2,3,4)
InChIKey: NBIIXXVUZAFLBC-UHFFFAOYSA-N

Open in ReactionLens Use in reaction prediction

Measured properties

Published measurements, each with its source. Two readings of one property are both shown, in the units each used.

Boiling Point: greater than 266 °F at 760 mmHg (USCG, 1999)measured · CAMEO Chemicals; 407 °Cmeasured · Hazardous Substances Data Bank (HSDB)
Melting Point: 108 °F (NIOSH, 2024)measured · CAMEO Chemicals; 42.4 °Cmeasured · Hazardous Substances Data Bank (HSDB)
Density: 1.892 at 77 °F (USCG, 1999) - Denser than water; will sinkmeasured · CAMEO Chemicals; 1.8741 (100% solution); 1.6850 (85% solution); 1.334 (50% solution), all at 25 °C /Phosphoric acid solutions/measured · Hazardous Substances Data Bank (HSDB)
Solubility: Miscible (NIOSH, 2024)measured · CAMEO Chemicals; Soluble in water, alcohol; soluble in 8 volumes of 3:1 ether:alcohol mixturemeasured · Hazardous Substances Data Bank (HSDB)
Vapor Pressure: 0.03 mmHg (NIOSH, 2024)measured · CAMEO Chemicals; 0.02 [mmHg]measured · Haz-Map, Information on Hazardous Chemicals and Occupational Diseases
LogP: -2.150measured · Human Metabolome Database (HMDB); -0.77 (estimated)measured · ILO-WHO International Chemical Safety Cards (ICSCs)
Viscosity: 3.86 mPa.s (40% solution at 20 °C).measured · Environment Canada; Tech Info for Problem Spills: Phosphoric Acid (Draft) p.4 (1982); 40 mm²/s at 20 °Cmeasured · reference compound database
Refractive Index: Index of refraction: 1.34203 at 17.5 °C/D, 10% solution; 1.35032 at 17.5 °C/D, 20% solution; 1.35846 at 17.5 °C/D, 30% solution /Phosphoric acid solutions/measured · O'Neil, M.J. (ed.). The Merck Index - An Encyclopedia of Chemicals, Drugs, and Biologicals. Whitehouse Station, NJ: Merck and Co., Inc., 2006., p. 1266

Calculated properties

Derived from the structure, not from a sample; kept apart from the measurements above.

Molecular weight: 97.995 g/molcalculated · reference compound database; Average mass of one molecule, from reference compound database.
Exact mass: 97.97689557 Dacalculated · reference compound database; Mass of the most common isotopic form.
XLogP3: -2.1calculated · reference compound database; Estimated oil/water partition, computed by reference compound database.
Polar surface area: 77.8 Å²calculated · reference compound database; Polar surface area as computed by reference compound database.
Complexity: 49calculated · reference compound database; A rough measure of how intricate the structure is.
H-bond donors: 3calculated · reference compound database
H-bond acceptors: 4calculated · reference compound database
logP: -0.9286calculated · chemistry engine; Estimated preference for oil over water. Higher means more oil-like.
Topological polar surface area: 77.76 Å²calculated · chemistry engine; Surface area from polar atoms; relates to how easily a molecule crosses membranes.
H-bond donors: 3calculated · chemistry engine; Atoms that can donate a hydrogen bond.
H-bond acceptors: 1calculated · chemistry engine; Atoms that can accept a hydrogen bond.
Rotatable bonds: 0calculated · chemistry engine; Single bonds the molecule can freely twist around.
Molar refractivity: 14.2629 cm³/molcalculated · chemistry engine; Relates to the molecule's polarisability.
Fraction sp³ carbons: 0calculated · chemistry engine; Share of carbon atoms with tetrahedral bonding.
QED drug-likeness: 0.3419calculated · chemistry engine; Quantitative estimate of drug-likeness (0–1).

What it is made of

Elements

O Oxygen4 atoms · 65.3% by mass
P Phosphorus1 atom · 31.6% by mass
H Hydrogen3 atoms · 3.1% by mass

Percentages are of the molecular weight above, worked out the same way the molar mass calculator does it.

Structure

Heavy atoms, hydrogen excluded: 5
Total atoms, hydrogen included: 8
Rings: 0
Aromatic rings: 0
Stereocentres: 0
Formal charge: 0

Functional groups

Phosphate
A phosphorus centre bonded to four oxygens.

Matched by structural pattern, not by a measurement.

The molecule in three dimensions

Rotate and inspect the atoms. Loaded only when you ask, so the page stays light.

The drawing above is a diagram of what is bonded to what. A molecule is not flat, and the model here is one low-energy shape generated from the connectivity — useful for seeing which groups can reach each other, and not a measured structure. A real sample is a population of conformations, interconverting.

Reactions it appears in

No documented reaction with a written procedure and a source involves Phosphoric Acid yet.

Other names for it

The systematic name on this record is phosphoric acid.

The sources also call it ORTHOPHOSPHORIC ACID, o-Phosphoric acid, Wc-reiniger, Acidum phosphoricum, Sonac, Phosphorsaeure, Evits, Acide phosphorique, Phosphoricum acidum, Acido fosforico, Phosphorsaeureloesungen.

Structurally related

Nothing structurally close to Phosphoric Acid has a page here yet.

Where these values came from

reference compound database1004
compound record
chemistry engine
structure perception

compound record.

What this page does not claim

Identifiers are copied from the source record, measured values are reported as published, and calculated values are marked as calculated. Nothing here is a hazard, purity or handling assessment — how the library is checked.