lead phosphide is an off-white, crystalline powder that is toxic. It reacts with water to form phosphine, which in turn forms a variety of complex compounds including metal-phosphorus phosphides. These compounds are often very poisonous and can cause lung damage, skin irritation, and even death. The toxicity of lead phosphide is due to its high vapor pressure and low melting point. It is also highly soluble in hydrochloric acid, nitric acid, fixed alkali hydroxides, and aqueous sulfuric acid.
The chemical structure of a phosphorus-metal phosphide is very diverse and seems to depend on steric and electronic effects. The phosphides of the electropositive alkali metals and alkaline-earth metals have properties that are close to metallic, while those of the later transition metals exhibit features of the ionic bonding system. The classification of phosphides into categories is complicated by the fact that they will react with other phosphides to yield different stoichiometry.
In drinking water treatment, phosphate is used to inhibit lead release from service lines and premise plumbing. However, phosphorus adsorption on lead phosphite particles makes the particles more negatively charged and promotes their aggregation. In the presence of organic carbon, this aggregation is retarded, resulting in reduced formation of disinfection byproducts.
In the production of this compound, a quantity of metal lead is added to a reactor where it is melted and dissolved with acetic acid. This is then mixed with phorous acid quantitatively and stirred for reaction, after which the product is filtered and dried. The resulting product is known as dibasic lead phosphite and is used to stabilize PVC hard and soft products, especially in outdoor cable and wire, building boards (such as corrugated board), pipe, etc.