Nitric acid manufacture via the Ostwald process Tamil revision mind map presented as a vertical three-stage cascade: raw materials ammonia and air in a nine to twelve to one ratio, step one catalytic oxidation of ammonia over a platinum-rhodium gauze at about 1100 Kelvin giving nitric oxide at 97 percent yield, step two cooling to about 150 degrees Celsius to oxidise nitric oxide to nitrogen dioxide, step three absorption of nitrogen dioxide in water in a packed tower to give nitric acid at about 96 percent yield with the nitric oxide by-product recycled back to step two, and the uses of nitric acid in fertilisers, explosives, nitrates and aqua regia.