Potassium Fluoride

Potassium fluoride is the <a href="http://en.wikipedia.org/wiki/Chemical_compound" title="Chemical compound" >chemical compound</a> with the formula KF. After <a href="http://en.wikipedia.org/wiki/Hydrogen_fluoride" title="Hydrogen fluoride" >hydrogen fluoride</a>, KF is the primary source of the <a href="http://en.wikipedia.org/wiki/Fluoride" title="Fluoride" >fluoride</a> ion for applications in manufacturing and in chemistry.

It is an <a href="http://en.wikipedia.org/wiki/Alkali_halide" title="Alkali halide" class="mw-redirect" >alkali halide</a> and occurs naturally as the rare <a href="http://en.wikipedia.org/wiki/Mineral" title="Mineral" >mineral </a><a href="http://en.wikipedia.org/wiki/Carobbiite" title="Carobbiite" >carobbiite</a>. Aqueous solutions of KF will etch glass due to the formation of soluble fluorosilicates, although <a href="http://en.wikipedia.org/wiki/Hydrofluoric_acid" title="Hydrofluoric acid" >HF</a> is more effective.

Like other sources of the fluoride ion, F−, KF is poisonous, although lethal doses approach gram levels for humans. It is harmful by inhalation and ingestion. It is highly corrosive, and skin contact may cause severe burns.

Potassium fluoride is prepared by dissolving <a href="http://en.wikipedia.org/wiki/Potassium_carbonate" title="Potassium carbonate" >potassium carbonate</a> in excess <a href="http://en.wikipedia.org/wiki/Hydrofluoric_acid" title="Hydrofluoric acid" >hydrofluoric acid</a>. Evaporation of the solution forms crystals of <a href="http://en.wikipedia.org/wiki/Potassium_bifluoride" title="Potassium bifluoride" >potassium bifluoride</a>. The bifluoride on heating yields potassium fluoride:

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The salt must not be prepared in glass or porcelain vessels as HF and the aqueous solution of KF corrode glass and porcelain. Heat resistant plastic or platinum containers may be used.