Hydrogen Cyanide
. Hydrogen Cyanide, also called hydrocyanic acid and prussic acid, extremely poisonous, colorless liquid with a bitter-almond odor. The compound's chemical formula is HCN, the term cyanide applying to the -CN structure. HCN melts at -14° C (6.8° F) and boils at 25.7° C (78.2° F). A few milligrams of the substance and of related cyanides can be rapidly fatal to humans, acting by blocking the ability of cells to use oxygen. The compound mixes with water, alcohol, and ether in all proportions. When impurities are present, HCN molecules can combine to form a black solid; the reaction may be explosive unless inhibited. HCN is flammable and can form explosive mixtures with air. It was once produced from the pigment Prussian blue, hence its secondary name. Now it is prepared commercially by the reaction of methane with ammonia in the presence of a platinum catalyst. One major use of HCN has been in the production of acrylonitrile , a starting compound for various products; however, this p