The Chemistry of Acid Rain
Key ConceptsRain from an unpolluted atmosphere has a pH close to 6.0 (slightly acidic).
This acidity is due to the reaction of water vapour and non-metal oxides in the atmosphere, such as carbon dioxide and nitrogen oxide, forming dilute acids.
Acid rain has a pH below 5.6 due mainly to the reaction of water vapour with sulfur dioxide and the oxides of nitrogen.
Sources of the acids in clean and polluted air
Effects of Acid Rain
Acid rain is a form of environmental pollution that damages buildings and marble statues by reacting with the calcium carbonate to form soluble calcium hydrogen carbonate (calcium bicarbonate, Ca(HCO3)2)
Acid rain can leach aluminium from the soil into ground water, lakes and rivers, poisoning fish and plant roots.
The sulfates and hydrogen sulfates in acid rain can can leach essential plant nutrients such as calcium and magnesium, from the soil.
Acid rain disrupts the process of photosynthesis resulting in damage to plant life.
At low concentrations it retards the production of chlorophyll and at high concentrations it forms sulfuric acid which kills the plant.
Some organisms are sensitive to changes of acidity in water which can affect their ability to reproduce and in some cases may kill them.