What is another word for pyrosulfuric acid?
Pronunciation: [pˌa͡ɪɹə͡ʊsʌlfjˈʊɹɪk ˈasɪd] (IPA) 
Pyrosulfuric acid is a strong hygroscopic and corrosive acid, commonly known as fuming sulfuric acid. Its chemical formula is H2S2O7 and it is derived from sulfuric acid by removing one molecule of water. Pyrosulfuric acid is also called oleum, Nordhausen acid, and fuming sulfuric acid. However, oleum refers to the mixture of sulfuric acid and sulfur trioxide. Similarly, Nordhausen acid is a historic term for pyrosulfuric acid. Fuming sulfuric acid refers to its high vapor pressure and the presence of sulfur trioxide. In industries, pyrosulfuric acid is used for nitration, sulfonation, and dehydration reactions. Despite its significant applications, pyrosulfuric acid is a hazardous substance and requires careful handling.
