A colourless dense, oily corrosive liquid produced by the reaction of sulphur trioxide with water and used in accumulators and the manufacture of fertilizers, dyes, and explosives. Sulphuric acid (British spelling), also known as oil of vitriol, is a mineral acid composed of the elements sulphur, oxygen and hydrogen, with molecular formula H2SO4. Sulphuric acid is also a key substance in the chemical industry. Sulphuric acid is called 'King of Chemicals' because of its extensive use in a large number of industries. Sulphuric acid is a powerful protonating agent. It is also a moderately strong oxidizing agent. Sulphuric acid is also a powerful dehydrating agent and is used to remove a molecule of water from many organic compounds.