Acid rain Acid rain Acid rain is a rain or any other form of precipitation that is unusually acidic, meaning that it has elevated levels of hydrogen ions (low pH). It can have harmful effects on plants, aquatic animals and infrastructure. Acid rain is caused by emissions of sulphur dioxide and nitrogen oxide, which react with the water molecules in the atmosphere to produce acids. Some governments have made efforts since the 1970s to reduce the release of sulphur dioxide and nitrogen oxide into the atmosphere with positive results. Nitrogen oxides can also be produced naturally by lightning strikes, and sulphur dioxide
Lead chamber process Sulfuric acid produced in the reaction chambers is limited to about 35% concentration. At higher concentrations, nitrosylsulfuric acid precipitates on the lead walls as chamber crystals and is no longer able to catalyze the oxidation reactions. Sulfur dioxide is generated by burning elemental sulfur or by roasting pyritic ore in a current of air: Nitrogen oxides are produced by decomposition of niter in the presence of sulfuric acid or hydrolysis of nitrosylsulfuric acid: In the reaction chambers, sulfur dioxide and nitrogen dioxide dissolve in the reaction liquor. Nitrogen dioxide is hydrated to produce nitrous acid which then oxidizes the sulfur