Fluorophosphoric acid

Fluorophosphoric acid
Names

IUPAC name Fluorophosphonic acid^[1]
Other names Fluorophosphoric acid^[1] Monoluorophosphoric acid^[1] Phosphorofluoridic acid^[1]
Identifiers
CAS Number	13537-32-1
3D model (JSmol)	Interactive image
ChEBI	CHEBI:30210
ChemSpider	22687
ECHA InfoCard	100.202.790
EC Number	233-433-0
Gmelin Reference	100863
PubChem CID	24267
UNII	IW87A7KU3R
CompTox Dashboard (EPA)	DTXSID1075309
InChI InChI=1S/FH2O3P/c1-5(2,3)4/h(H2,2,3,4) Key: DWYMPOCYEZONEA-UHFFFAOYSA-N
SMILES OP(=O)(O)F
Properties
Chemical formula	H₂PO₃F
Molar mass	99.985 g·mol⁻¹
Appearance	Colorless liquid^[1]
Odor	Practically odorless^[1]
Density	1.818 g/cm³^[1]
Melting point	−78 °C (−108 °F; 195 K)^[1]
Boiling point	Decomposes
Solubility in water	yes
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Causes skin burns and eye damage.
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301, H311, H314, H330
Precautionary statements	P260, P264, P270, P271, P280, P284, P301+P310, P301+P330+P331, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P310, P312, P320, P321, P322, P330, P361, P363, P403+P233, P405, P501
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Chemical compound

Fluorophosphoric acid is the inorganic compound with the formula H₂PO₃F. It is a colorless viscous liquid that solidifies to a rigid glass upon cooling at −78 °C (−108 °F).^[2]^[1]

Preparation

Fluorophosphoric acid is produced commercially by treating phosphorus pentoxide with hydrogen fluoride. A less pure product can also be prepared by hydrolysis of phosphorus oxyfluoride, a reaction that first produces difluorophosphoric acid:^[2]

POF₃ + H₂O → HPO₂F₂ + HF

The next steps give monofluorophosphoric acid:

HPO₂F₂ + H₂O → H₂PO₃F + HF

Reactions

Fluorophosphoric acid is a dibasic acid, with pK_a1 of 5.5 and pK_a2 of around 8.5.^[1] The conjugate bases are the monofluorophosphates, which are hydrolytically robust. When fluorophosphoric acid is diluted with water, it hydrolyzes, producing phosphoric acid. Fluorophosphoric acid is not flammable.^[1]

Uses

Fluorophosphoric acid is used to make protective coatings on metal surfaces, as a metal cleaner and as an electrolytic or chemical polishing agent. The sodium salt of this acid, sodium monofluorophosphate, is the most used dentifrice additive for the reduction of tooth decay.^[1]

Safety

Fluorophosphoric acid is corrosive to living tissue. It can cause severe skin burns and permanent eye damage. Ingestion can cause severe burns and permanent damage to gastrointestinal system. Inhalation of this acid may cause severe burns to respiratory system and chemical pneumonia. Inhalation, ingestion or contact with skin with this acid may cause severe injury or death. Symptoms from contact or inhalation may be delayed.^[1]

References

^ ^a ^b ^c ^d ^e ^f ^g ^h ⁱ ^j ^k ^l ^m https://pubchem.ncbi.nlm.nih.gov/compound/Fluorophosphoric-acid
^ ^a ^b Charles B. Lindahl; Tariq Mahmood (2000). "Fluorine Compounds, Inorganic, Phosphorus". Kirk‐Othmer Encyclopedia of Chemical Technology. doi:10.1002/0471238961.1608151912091404.a01. ISBN 978-0-471-48494-3.