Sulphuric acid is formed by the oxidation of sulphide minerals. An example of a sulphide mineral is iron sulphide. It is dense, colorless, and oily. It is capable of dissolving metals and many organic materials.
There are two commercial processes by which it is made. The lead chamber process and the contact process. The lead chamber process involves the oxidation of sulfur dioxide. This is done by using nitric acid with water. The reaction occurs in large lead rooms. The contact process occurs when sulphur dioxide is converted into sulfur trioxide. The sulfur trioxide reacts with water and sulphuric acid is the product.
It is very important in industry. Some things it is used for is petroleum refining, fertilizer, dyes, explosives, and detergents.
There are two main processes used in the production of H2SO4, lead chamber process and contact process. Lead process chamber is an old method, and it produces a solution of acid in water, of concentration 62-78%. Through the contact process, sulfuric acid is obtained easily. In both processes, sulfur dioxide, SO2 is oxidized to sulfur trioxide, SO3, which is dissolved in water.
Sulphur dioxide is produced by burning of sulfur:
S (s) + O2 (g) --> SO 2 (g)
by roasting pyrite (iron sulphide) or other metal sulfides
4 Fes (s) + 7 O2 (g) --> 2 Fe2O3 (s) + 4 SO 2 (g)
or by burning hydrogen sulphide
2 H2S (g) + 3 O2 (g) --> 2 SO2 (g) +2 H2O (g)
Sulfur dioxide is catalytically oxidized to sulfur trioxide
2SO2 (g) + O2 (g) --> 2 SO3 (g)
In the absence of catalyst, oxidation of SO2 is slow. In the old lead chamber process, the catalyst is azot carbon dioxide. In contact process, the catalyst is vanadium oxide, V2O5. Sulfur trioxide is dissolved in 98% sulfuric acid, it is reacting with 2% water to form H2SO4.
SO3 (g) + H2O (l) --> H2SO4 (l)