Hydrofluroric Acid

Hydrofluoric acid (HF) is a <a href="http://en.wikipedia.org/wiki/Solution" title="Solution" >solution</a> of <a href="http://en.wikipedia.org/wiki/Hydrogen_fluoride" title="Hydrogen fluoride" >hydrogen fluoride</a> in<a href="http://en.wikipedia.org/wiki/Water" title="Water" >water</a>. It is a valued source of <a href="http://en.wikipedia.org/wiki/Fluorine" title="Fluorine" >fluorine</a> and is a precursor to numerous pharmaceuticals such as <a href="http://en.wikipedia.org/wiki/Fluoxetine" title="Fluoxetine" >fluoxetine</a> (<a href="http://en.wikipedia.org/wiki/Prozac" title="Prozac" class="mw-redirect" >Prozac</a>) and diverse materials such as <a href="http://en.wikipedia.org/wiki/Polytetrafluoroethylene" title="Polytetrafluoroethylene" >PTFE</a> (Teflon).

Hydrofluoric acid is a highly corrosive acid, capable of dissolving many materials, especially <a href="http://en.wikipedia.org/wiki/Oxide" title="Oxide" >oxides</a>. Its ability to dissolve glass has been known since the 17th century, even before hydrofluoric acid had been prepared in large quantities by <a href="http://en.wikipedia.org/wiki/Carl_Wilhelm_Scheele" title="Carl Wilhelm Scheele" >Carl Wilhelm Scheele</a> in 1771.<a href="http://en.wikipedia.org/wiki/Hydrofluoric_acid#cite_note-1" >[2]</a> Because of its high reactivity toward glass and moderate reactivity toward many metals, hydrofluoric acid is usually stored in plastic containers (although <a href="http://en.wikipedia.org/wiki/Polytetrafluoroethylene" title="Polytetrafluoroethylene" >PTFE</a> is slightly permeable to it).<a href="http://en.wikipedia.org/wiki/Hydrofluoric_acid#cite_note-Ullmann-2" >[3]</a>

Hydrogen fluoride gas is a severe poison that may immediately and permanently damage lungs and the corneas of the eyes.<a href="http://en.wikipedia.org/wiki/Aqueous" title="Aqueous" class="mw-redirect" >Aqueous</a> hydrofluoric acid is a contact-poison with the potential for deep, initially painless burns and ensuing tissue death. By interfering with body calcium metabolism, the concentrated acid may also cause systemic toxicity and eventual cardiac arrest and fatality, after contact with as little as 160 cm2 (25 square inches) of skin.