Hydrogen fluoride

 

Hydrogen fluoride

Chemical formula	HF
OTP appearance	ultra-pale yellow gas
Molar Mass(g/mol)	20.01
Density(g/cc)	.00115
Melting Point(°C)	-83.6
Boiling Point(°C)	19.5
NFPA 704	0 4 1

Uses

Primary

• Key fluorine ion source
• Feedstock for industrial chemical hydrofluoric acid
• Feedstock for sodium aluminum hexafluoride, essential for aluminum production

Natural occurrence

• Hydrogen fluoride does not occur naturally.

Hazards

This is a highly dangerous substance.

• Pure gaseous hydrogen fluoride is toxic and corrosive. It is very dangerous.
• Aqueous hydrogen fluoride (hydrofluoric acid) is also toxic and corrosive, but less so.

Treatment

• Intravenous (IV) magnesium sulfate and intra/trans-dermal calcium gluconate are sometimes used after cutaneous exposure to hydrofluoric acid

Production

Synthesis

Combine and heat sulfuric acid with fluorite or fluorapatite, producing hydrofluoric acid.

CaF₂ + H₂SO₄ → CaSO₄ + 2 HF

2 Ca₅(PO₄)₃F + 7 H₂SO₄ + 3 H₂O → 7 CaSO₄ + Ca₃(PO₄)₂ + H₃PO₄ + 2 HF

Storage

Hydrogen fluoride must be stored in polyethylene (LDPE, HDPE, etc) or fluorinated versions thereof (PTFE/teflon). Container-in-container storage is preferred. Magnesium sulfate can be used to absorb spills.

Disposal

• First dissolve in water, producing more manageable hydrofluoric acid. Then dispose of that.