Question

How is oleum made from sulfur by the contact process?

Answer 1

Adding an excess of oxygen to sulfur dioxide in the presence of the catalyst vanadium pentoxide at 450 °C and 1-2 atm. The sulfurtrioxide formed is added to sulfuric acid which gives rise to oleum (disulfuric acid) Theoleum is then added to water to form sulfuric acid which is very concentrated