Pyrosulfuric acid is strong in nature and taken as the major constituent of fuming sulfuric acid. The other name for the compound is disulfuric acid too. The chemical formula for pyrosulfuric acid is H2O7S2 with a molecular weight of 178.13 g/mol.
The structure of the molecule is given below and formed by combining two molecules of sulfuric acid and followed by the dehydration of one water molecule.
The acid is prepared by mixing dissolving sulfur trioxide and concentrated sulfuric acid together. It can also be obtained by quick preparation of the sulfuric acid by the contact process. It is colorless crystalline solid with a melting point around 36 degree Celsius and it is not available in 100 percent pure form but in fuming, a dense or oily liquid form that could be colorless to dark brown any color based on the physical properties of the chemical.
The chemical properties of this acid highly similar to the sulfuric acid but a much weaker acid when compared to sulfuric ones. It also reacts with bases quickly to from pyrosulphates and decomposes readily on heating to release sulfuric acid and the water.
The major usage of the acid is considered in manufacturing explosives or dyes. It is also used for petroleum refining and a suitable intermediate for storage or transportation. Also, it is less corrosive in nature but the health hazards are also similar to the sulfuric acid. Further, this is a powerful dehydrating agent can cause severe irritation to eyes and respiratory tract.