air in the presence of a catalyst such as V O or platinised asbestos. iii. The sulphur trioxide is absorbed in concentrated sulphuric acid and produces oleum (H S O ). The oleum is converted into sulphuric acid by diluting it with water.
SO + H SO H S O 2H SO H O → To maximise the yield the plant is operated at bar pressure and K. The sulphuric acid obtained in this process is over % pure. Physical properties: Pure sulphuric acid is a colourless, viscous liquid (Density: . g/mL at K).
High boiling point and viscosity of sulphuric acid is due to the association of molecules together through hydrogen bonding. The acid freezes at . K and boils at K. It is highly soluble in water and has strong affinity towards water and hence it can be used as a dehydrating agent.
When dissolved in water, it forms mono (H SO .H O) and dihydrates (H SO .2H O) and the reaction is exothermic. The dehydrating property can also be illustrated by its reaction with organic compounds such as sugar, oxalic acid and formic acid. C H O + H SO 12C + H SO .11H O HCOOH Sucrose Formic acid Oxalic acid + H SO CO + H SO .H O (COOH) + H SO CO + CO + H SO .H O Chemical Properties: Sulphuric acid is highly reactive. It can act as strong acid and an oxidising agent.
Decomposition: Sulphuric acid is stable, however, it decomposes at high temperatures to sulphur trioxide. H SO H O + SO Acidic nature: It is a strong dibasic acid. Hence it forms two types of salts namely sulphates and bisulphates. H SO + NaOH NaHSO + H O H SO + 2Na sodium bisulphate OH Na SO + 2H O H SO + 2NH (NH ) sodium sulphate Ammonium sulphate SO Oxidising property: Sulphuric acid is an oxidising agent as it produces nascent oxygen as