695017 Sigma-Aldrich

Phosphoric acid

ACS reagent, ≥85 wt. % in H2O

Synonym: Orthophosphoric acid

  • CAS Number 7664-38-2

  • Linear Formula H3PO4

  • Molecular Weight 98.00

  •  Beilstein/REAXYS Number 1921286

  •  EC Number 231-633-2

  •  MDL number MFCD00011340

  •  PubChem Substance ID 329761708

  •  NACRES NA.21



Related Categories Acids, Acids & Bases, Chemical Synthesis, Inorganic Acids, Synthetic Reagents More...
Quality Level   200
grade   ACS reagent
vapor density   3.4 (vs air)
vapor pressure   2.2 mmHg ( 20 °C)
  5 mmHg ( 25 °C)
assay   ≥85% H3PO4 basis (by NaOH, titration)
form   liquid
concentration   ≥85 wt. % in H2O
application(s)   NMR: suitable
impurities   reducing substances, passes test
  ≤0.001% volatile acids (as CH3COOH)
color   APHA: ≤10
bp   158 °C (lit.)
mp   ~40 °C (lit.)
density   1.685 g/mL at 25 °C (lit.)
anion traces   chloride (Cl-): ≤3 ppm
  nitrate (NO3-): ≤5 ppm
  sulfate (SO42-): ≤0.003%
cation traces   As: ≤1 ppm
  Ca: ≤0.002%
  Fe: ≤0.003%
  K: ≤0.005%
  Mg: ≤0.02%
  Mn: ≤0.5 ppm
  Na: ≤0.025%
  Sb: ≤0.002%
  heavy metals (as Pb): ≤0.001%
SMILES string   OP(O)(O)=O
InChI   1S/H3O4P/c1-5(2,3)4/h(H3,1,2,3,4)
Gene Information   human ... SRC(6714)


General description

Phosphoric acid (H3PO4) is useful in industry for treating the metal surfaces to obtain better adhesion of paint and resin coatings.


Phosphoric acid may be employed as standard for the determination of phosphorus-31 nuclear magnetic resonance (31P NMR) chemical shifts of the common phospholipids. It may be employed in the following studies:
• As external standard for the analysis of lipid composition of human white matter by 31P NMR spectroscopy.
• As external standard during the acid-labile phosphorylation of histone H4 by 31P NMR spectroscopy.
• As reference standard to investigate the surface species present on silica/alumina-supported sodium phosphates by pre- and postreaction MAS31P-NMR and FTIR spectroscopies.
• As catalyst in the vapor-phase Fries rearrangement of phenylacetate at 623K over a series of surface modified and unmodified ZSM-5.


100, 12×100, 500 mL in poly bottle

2.5 L in poly bottle

Other Notes

Concentrated phosphoric acid is approx. 85% H3PO4 (aqueous).

Safety & Documentation

Safety Information

Signal word 
Hazard statements 
UN 1805 8 / PGIII
WGK Germany 
Flash Point(F) 
Not applicable
Flash Point(C) 
Not applicable


Certificate of Analysis (COA)

Please Enter a Lot Number

Certificate of Origin (COO)

Please Enter a Lot Number
Protocols & Articles


Enzymatic Assay of Endoproteinase Glu-C (EC

This procedure may be used for determination of Endoproteinase Glu-C enzymatic activity using N-t-Boc-L-glutamic acid α-phenyl ester as the substrate. This continuous UV spectrophotometric rate deter...
Keywords: Digestions, Enzyme activity, Extinction coefficient

Related Content

Lab Chemicals

We are a leading global supplier and manufacturer of high-quality, stockroom and basic research products including solvents, acids and inorganics. We specialize in providing the most comprehensive pr...
Keywords: Solvents

Molarity Calculator & Normality Calculator for Acids & Bases

The molarity calculator tool provides lab-ready directions describing how to prepare an acid or base solution of specified Molarity (M) or Normality (N) from a concentrated acid or base solution. To ...

Peer-Reviewed Papers


Related Products

Technical Service:

Our team of scientists has experience in all areas of research including Life Science, Material Science, Chemical Synthesis, Chromatography, Analytical and many others.

Bulk Ordering & Pricing:

Need larger quantities for your development, manufacturing or research applications?