an oily, hygroscopic, corrosive liquid, H2S2O7, that, depending on purity, is colorless or dark brown: used chiefly as a dehydrating agent in the manufacture of explosives and as a sulfating or sulfonating agent in the manufacture of dyes.
Origin of pyrosulfuric acid
First recorded in 1870–75
Also called fuming sulfuric acid, oleum.
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2019
A heavy, oily, colorless to dark brown liquid produced by adding sulfur trioxide to concentrated sulfuric acid. It is used in petroleum refining and the manufacture of explosives. Chemical formula: H2S2O7.
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