Hydrofluoric acid

 

Hydrofluoric acid

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 0 ACID

Uses

Primary

• Production of aluminum
• Key fluorine transport

Natural occurrence

Hydrofluoric acid 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 intradermal 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

Hydrofluoric acid 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

• Combine with sodium hydroxide or potassium hydroxide, yielding tame-er alkali fluorides
• Combine with Tin (II) oxide, (SnO) producing stannous fluoride, a GRAS dental fluorinating agent.

  SnO + 2 HF

  {

  →

  60°C}

  SnF₂ + H₂O