Acid reacts with water to form carbonic acid:CO2(g)+H20(l)

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 is produced by volcanic eruptions. Acid rain has been shown to have adverse impacts on forests, freshwaters and soils, killing insect and aquatic life-forms, causing paint to peel, corrosion of steel structures such as bridges, and weathering of stone buildings and statues as well as having impacts on human health.FORMATION:Acid rain is a rain that has Ph value lower than 5.6. Acid rain posses high level of H+ ions. Acid rain can be classified based on the type of acid: a) carbonic acid (H2CO3) b) sulfuric acid (H2SO4) c) nitrous acid (HNO2) and nitic acid (HNO3).a) Carbonic acidCarbon dioxide reacts with water to form carbonic acid:CO2(g)+H20(l) H2CO3(l)b) Sulfuric acidSulphur dioxide is oxidised to form sulphur trioxide:2SO2(g)+O2(g) 2SO3(g)Sulphur trioxide then reacts with water to form sulphuric acid.S03(g)+ H2O(l) H2SO4(l)c) Nitrous acid and nitic acidNitrogen reacts with oxygen to form nitric acid:N2(g)+O2(g) 2NO(g)Nitric oxide is a very reactive compound. It is further oxidised to form nitrogen dioxide:N2(g)+O2(g) 2NO2(g)Nitrogen dioxide reacts with water to form nitrous acid and nitric acid;2NO2(g)+H2O(l) HNO2(l)+HNO3(l)Addition of water to acidic gases is important to show its acidic properties. Without the addition of water, the acidic properties cannot be shown. The acid can be ionized to form H+ ion which is responsible for the acidic property.H2CO3(l) H+ +HCO3-H2SO4(l) H+ +HSO4-HNO3(l)  H+ +NO3-Acid rain can be formed is mainly because acidic gases react with water vapour in cloud  or atmosphere.CAUSES OF ACID RAIN:Acid rain is caused by either natural phenomenon or human activities.Natural phenomenaThe principal natural phenomena that contribute acid-producing gases to the atmosphere are emissions from volcanoes. #Reaction with water and carbon dioxideCO2 can dissolve in water vapour in air to form carbonic acid:CO2(g)+H2O(l) H2CO3(l)# Lighting and thunderstormLighting can form a large amount of heat energy, which is able to ionize atmospheric nitrogen and oxygen to form free radical:N+O NO2NO(g)+O2(g) 2NO2(g)2NO(g)+H2O(l) HNO2(l)+HNO3(l)#Volcanic eruptionsLava in volcano contains high amount of sulphur content, which leads to formation of sulphuric acid rain:2SO2(g)+O2(g) 2SO3(g)SO3(g)+H2O(l) H2SO4(l)Human activity:#Petroleum combustion in vehiclesCombustion of petroleum in vehicles contributes to nitric and nitrous acid rain.#Industry sectorFactories emit sulphur dioxide that causes sulphur acid rain. The coal-fired Gavin Power Plant in Cheshire, Ohio#Open burningOpen burning emits carbon dioxide that causes carbonic acid rain. Chemical processesCombustion of fuels produces sulphur dioxide and nitric oxides. They are converted into sulfuric acid and nitric acid. This shows the process of the air pollution being released into the atmosphere and the areas that will be affected.EFFECT OF ACID RAIN:1. AFFECTS MARINE ECOSYSTEMAquatic organisms may be killed as they cannot adapt to low Ph.2. DESTROY FORESTSThe ph of the soils will decreases. This will destroy the tree leaves. The rate of photosynthesise in plant will decrease.3. PUBLIC HEALTHIt will weaken the immune system of humans. It can also cause skin diseases4. Corrosion of metalStructure made of metal may be corroded. For example body of cars.5. Forests and other vegetation Acid rain can have severe effects on vegetation. A forest in the Black Triangle in Europe.Adverse effects may be indirectly related to acid rain, like the acid’s effects on soil or high concentration of gaseous precursors to acid rain. High altitude forests are especially vulnerable as they are often surrounded by clouds and fog which are more acidic than rain.Other plants can also be damaged by acid rain, but the effect on food crops is minimized by the application of lime and fertilizers to replace lost nutrients. In cultivated areas, limestone may also be added to increase the ability of the soil to keep the pH stable, but this tactic is largely unusable in the case of wilderness lands. When calcium is leached from the needles of red spruce, these trees become less cold tolerant and exhibit winter injury and even death.6. Other adverse effects Effect of acid rain on statues Acid rain and weatheringAcid rain can damage buildings, historic monuments, and statues, especially those made of rocks, such as limestone and marble, that contain large amounts of calcium carbonate. Acids in the rain react with the calcium compounds in the stones to create gypsum, which then flakes off.CaCO3 (s) + H2SO4 (aq) ? CaSO4 (s) + CO2 (g) + H2O (l)The effects of this are commonly seen on old gravestones, where acid rain can cause the inscriptions to become completely illegible. Acid rain also increases the corrosion rate of metals, in particular iron, steel, copper and bronze.WAYS TO PREVENT OR OVERCOME ACID RAIN:1. Desulfurization Harmful sulphur dioxide gas passes through aqueous calcium carbonate to produce less harmful carbon dioxide:CaCO3(aq) +SO2           CaSO3+ CO22. Liming (addition of lime or limestone)Lime or limestone CaOH combines with the sulphur dioxide to form CaSO3(s).Ca(OH)2(aq) + SO2  CaSO3(s) + H2O3. Vehicle controlIncomplete combustion of petroleum. For an example, combustion in insufficient oxygen supply. This causes production of harmful gases such as CO.4. Catalyst converterIt is installed in vehicles to convert harmful gases such as CO into less harmful gases such as CO2, H2o, by redox reaction