Cambridge O Level Chemistry · Syllabus 5070 · Chemistry of the Environment
Acid Rain
What is Acid Rain?
Rain made acidic by pollutant gases dissolved in atmospheric water. Sulfur dioxide, released when fossil fuels containing sulfur compounds are burned, and oxides of nitrogen, formed in car engines, are the two pollutants responsible. Acid rain damages buildings and structures made of limestone and of metal, and harms trees and life in lakes and rivers.
This definition is part of the Chemistry of the Environment chapter in Cambridge O Level Chemistry.
Acid Rain in context
Chemistry of the environment covers water, air and carbon as three linked systems. Water is tested for presence with cobalt(II) chloride or copper(II) sulfate, and for purity with a sharp melting point of about \(0\,{}^\circ\mathrm{C}\) and boiling point of about \(100\,{}^\circ\mathrm{C}\); a domestic supply is then treated by sedimentation and filtration, carbon filtration and chlorination. Clean dry air is about 78% nitrogen and 21% oxygen, and six pollutants — carbon dioxide, carbon monoxide, particulates, methane, oxides of nitrogen and sulfur dioxide — each have a distinct source and effect, such as acid rain or global warming. Carbon dioxide absorbed in photosynthesis links combustion back to plant growth.
Common mistakes with Acid Rain
- “Carbon dioxide causes acid rain.” Defect The effect belongs to a different pollutant. Chemistry Acid rain is caused by sulfur dioxide and oxides of nitrogen. The named effect of carbon dioxide is increased global warming and climate change. Repair Learn the pairs in blocks: climate for \(\mathrm{CO_2}\) and \(\mathrm{CH_4}\); acid rain for \(\mathrm{SO_2}\) and NOx. Transfer A limestone statue is eroding. Which two pollutants? Sulfur dioxide and oxides of nitrogen.
- “Sulfur dioxide is the main cause of global warming.” Defect The mirror image of the previous error. Chemistry Sulfur dioxide causes acid rain. The greenhouse gases named in this topic are carbon dioxide and methane. Repair Two gases for climate, two for acid rain — and none in both. Transfer Which control targets sulfur dioxide? Low-sulfur fuels, or flue gas desulfurisation with calcium oxide.
Questions students ask about Acid Rain
What is the source and effect of each of the six air pollutants?
Carbon dioxide comes from complete combustion of carbon-containing fuels and causes global warming. Carbon monoxide and particulates come from incomplete combustion; carbon monoxide is toxic and particulates increase respiratory problems and cancer risk. Methane comes from decomposing vegetation and animal digestion and also causes global warming. Oxides of nitrogen form in car engines and cause acid rain and photochemical smog. Sulfur dioxide comes from burning fossil fuels containing sulfur and causes acid rain.