Sulfures

Sulfures is not a standard term in English, but it is sometimes used informally to refer to sulfur and sulfur-containing compounds. The element sulfur (S) has atomic number 16 and is a nonmetal that occurs widely in nature, both as the pure element and in many minerals. Elemental sulfur is a bright yellow, brittle solid at room temperature, with a melting point of about 115°C and a boiling point around 445°C. It exists in several allotropes, including rhombic and monoclinic forms, and can form polymeric “plastic sulfur” when heated briefly above its melting point.

Occurrence and natural forms. Native sulfur is found near volcanic regions and hot springs. Sulfur is also present in numerous minerals as sulfides and sulfates; common sulfide minerals include pyrite (FeS2) and galena (PbS), while sulfates like gypsum (CaSO4) and barite (BaSO4) are widespread in sedimentary rocks. In the environment, sulfur cycles between several oxidation states and participates in various biogeochemical processes.

Chemical properties. In sulfur chemistry, oxidation states range from −2 in sulfides to +6 in sulfates, with 0 in elemental sulfur. Sulfur forms a wide array of compounds, including hydrogen sulfide (H2S), sulfur dioxide (SO2), sulfuric acid (H2SO4), and many organosulfur species. The combustion of sulfur or sulfur-containing fuels releases sulfur dioxide, a precursor to acid rain.

Uses and applications. The most important industrial process involving sulfur is the production of sulfuric acid via the contact process, essential to many chemical industries. Sulfur and sulfur compounds are also used in fertilizers, vulcanization of rubber, paper production, detergents, and various pharmaceuticals. Sulfur compounds play roles in vulcanization, odorants for industry, and as reagents in organic synthesis.

Environmental and health aspects. Emissions of sulfur oxides from burning sulfur-containing fuels contribute to air pollution and acidification of water bodies. Sulfur compounds can affect respiratory health and ecosystems, prompting regulatory controls and emission-reduction efforts.