Sulphuric acid manufacture via the Contact process Tamil revision mind map focused on the industrial plant, not the equilibrium reasoning covered separately in the Unit 12 map: burning purified molten sulphur to sulphur dioxide, the four-catalyst-bed vanadium pentoxide converter with inter-stage cooling reaching about 99.5 percent conversion, why sulphur trioxide is absorbed into concentrated sulphuric acid to form oleum rather than water directly since that would create a dangerous acid mist, diluting oleum in a controlled way to give sulphuric acid, and why excess cheap air is fed in to push the equilibrium toward more product.