Acidoleum

Acidoleum is a term that has been used historically to refer to oleum, which is a solution of sulfur trioxide (SO3) in concentrated sulfuric acid (H2SO4). It is also known as fuming sulfuric acid. The concentration of sulfur trioxide in oleum can vary, and it is often expressed as a percentage of free SO3.

Oleum is a highly corrosive and dangerous substance. It reacts exothermically with water, producing large amounts of heat and potentially causing dangerous splattering. It is also a strong oxidizing agent. Due to its hazardous nature, oleum is handled with extreme care and requires specialized equipment and safety precautions.

Historically, oleum was produced by the lead chamber process, but modern industrial production primarily uses the contact process. In the contact process, sulfur dioxide (SO2) is oxidized to sulfur trioxide (SO3) over a catalyst, typically vanadium pentoxide (V2O5). The sulfur trioxide is then absorbed into concentrated sulfuric acid to form oleum.

Oleum is an important industrial chemical. It is used in the production of dyes, explosives, detergents, pharmaceuticals, and other chemical products. It is also used in petroleum refining and as a sulfonating agent in organic synthesis. Its reactivity and ability to introduce sulfur-containing groups make it a valuable reagent in various chemical processes.