Hydrogen, an abundant element that helps power the sun, also forms diverse compounds on earth ranging from water to hydrogen sulfide: a foul-smelling, colorless gas that forms when bacteria decompose dead animal and plant matter in stagnant low-oxygen water. Although hydrogen sulfide causes serious health problems at high exposure levels, it has several important commercial uses ranging from metallurgy to manufacturing.
H2S at a Glance
Hydrogen sulfide and water have similar structures, but intermolecular forces in H2S are weaker than those in H2O. These weaker forces cause hydrogen sulfide to boil at a lower temperature than water. The human body, volcanic gases, unrefined petroleum and natural gas all contain hydrogen sulfide. This gas is heavier than air so it often accumulates in low-lying areas. Food processing plants, paper mills and other industries can also create H2S as a byproduct of their production processes.
Hydrogen Sulfide: Nature's Chemical Helper
The main use for hydrogen sulfide is in the production of sulfuric acid and elemental sulfur. Manufacturers use sodium hydrosulfide, sodium sulfide and similar inorganic sulfides to create products such as pesticides, leather, dyes and pharmaceuticals. H2S is used to prepare the inorganic sulfides you need to make those products. As a reagent and intermediate, hydrogen sulfide is beneficial because it can prepare other types of reduced sulfur compounds. A reagent is a starting participant in a chemical reaction. In a chemical process, an intermediate is a substance that the process creates. This substance, not the final product, can serve as raw material for the process's next step.
Other Important Uses
Some nuclear power plants use hydrogen sulfide to produce heavy water, an alternative to regular water that enables nuclear reactors to use ordinary uranium fuel instead of enriched uranium. Farmers use H2S as an agricultural disinfectant and you'll find it in some cutting oils, which are coolants and lubricants designed specifically for metalworking and machining processes, and other lubricants. Hydrogen sulfide is also used in chemical warfare. Many industrial entities, such as iron smelters, landfills, food processing plants and breweries, produce or use hydrogen sulfide. If one of them disposes of this gas improperly or releases it accidentally, unwanted emissions may escape into the air.
Make Your Own H2S
Although natural sources provide significant amounts of hydrogen sulfide, you can create it in a laboratory by adding an acid, such as concentrated sulfuric acid, to a sulfide, such as sodium sulfide. Distillation of petroleum also produces the gas. You may purchase H2S if you don't want to make it, but shipping regulations could affect its sale. H2S is in the same chemical asphyxiant class as cyanide and carbon monoxide, and is extremely toxic. Therefore, it's important to minimize exposure to this gas; 50 to 200 parts per million can cause problems ranging from eye irritation to death.