individuals may not detect it even at concentrations of 100 ppm. Anhydrous ammonia corrodes copper- and zinc-containing alloys which makes brass fittings not appropriate for handling the gas. Liquid ammonia can also attack rubber and certain plastics. Ammonia reacts violently with the halogens. Nitrogen triiodide, a primary high explosive, is formed when ammonia comes in contact with iodine. Ammonia causes the explosive polymerisation of ethylene oxide. It also forms explosive fulminating compounds with compounds of gold, silver, mercury, germanium or tellurium, and with stibine. Violent reactions have also been reported with acetaldehyde, hypochlorite solutions, potassium ferricyanide and peroxides. Production Ammonia has one of the highest rates of production of any inorganic chemical. Production is sometimes expressed in terms of 'fixed nitrogen'. Global production was estimated as being 160 million tonnes in 2020 (147 tons of fixed nitrogen). China accounted for 26.5% of that, followed by Russia at 11.0%, the United States at 9.5%, and India at 8.3%. Before the start of World War I, most ammonia was obtained by the dry distillation of nitrogenous vegetable and animal waste products, including camel dung, where it was distilled by the reduction of nitrous acid and nitrites with hydrogen; in addition, it was produced by the distillation of coal, and also by the decomposition of ammonium salts by alkaline hydroxides such as quicklime: For small scale laboratory synthesis, one can heat urea and calcium hydroxide: Haber–Bosch Mass production uses the Haber–Bosch process, a gas phase reaction between hydrogen () and nitrogen () at a moderately-elevated temperature (450 °C) and high pressure (): , ΔH° = −91.8 kJ/mol This reaction is exothermic and results in decreased entropy, meaning that the reaction is favoured at lower temperatures and higher pressures. It is difficult and expensive to achieve, as lower temperatures result in slower reaction kinetics (hence a slower reaction rate) and high pressure requires high-strength pressure vessels that are not weakened by hydrogen embrittlement. Diatomic nitrogen is bound together by a triple bond, which makes it rather inert. Yield and efficiency are low, meaning that the output must be continuously separated and extracted for the reaction to proceed at an acceptable pace. Combined with the energy needed to produce hydrogen and purified atmospheric nitrogen, ammonia production is energy-intensive, accounting for 1% to 2% of global energy consumption, 3% of global carbon emissions, and 3 to 5% of natural gas consumption. The choice of catalyst is