Page 1 :
ee eevanets also release sulphur dioxide on, combustion, , , , , , , , , , Some sources of oxides of sulphur are chemical, Plants, metai-processing plants and copper, lead and, zine justries,, , Sulphyt 4 non-metallic element found in coal, (fossit fui fuel oil. When these fuels are, burned, su, , , , we combines with oxygen in air to form, its gaseous oxides, sulphur dioxide (SO,) and, sulphur trioxide (SO,),, , S +0, > so,, 280, + 0, > 280,, Sulphur dioxide and sul, with water to form H,SO,, cause of acid rain,, 280, + 0, + 2H,0 + 2H,S0,, SO, + 1,0 > H,s0,, Impact of Acid Rain, , , , Iphur trioxide react, 4 Which is the main, , , , (i) Acid rain affects soil chemistry. It removes, calcium and potassium, both the basic, ingredients of soil, thus making it lose its, fertility, which ultimately damages forests, , Acid rain causes loss of nutrients from plants, thus damaging their leaves, ,, , (ii) anid rain has serious ecological impacts, as it, affects water bodies too. The water of lakes, , 1, Why does rain water have pH less than 7 9, 3, pH of acid rain is sometimes as low as, + Explain the formation of, , () oxides of sulphur, , , , (i) oxides of nitrogen, 4, What are the causes of acid rain 2, , EXCERCISE 8 (B) j, , 5. Give the impact of acid rain :, , , , , , eevee ( SaEen Saee ewe ame CURE Titey, inhaled air. In lower concentrations,, , > it injures, lung tissues., , Reducing the impact of Acid Rain :, , The impact of acid rain can be rediiced by, checking the root cause of acid rain,, reducing the emission of oxides of sulphur, nitrogen. This can be done by using cox, with low sulphur content., , We can also reduce such emissions by using, a scrubber, a device that absorbs gaseous, Pollutants. A scrubber used for removing sulphur, dioxide from a smoke stack usu: s, , e. by, ir and, 1 or oil, , Gas-diffusing, Plate, , ao, , , , , , , , , , , , , , , , Water in, n€, U s, __ > Water out, 8 Fig. 8.3.4 scrubber, —, , Scanned with CamScanner, , (i) on plants (ii) on soil, (iii) on water bodies., , 6. How does a scrubber help in reducing the formation, , of acid rain ?, , , , GLOBAL WARMING, , About three-fourth of the sun’s energy reaching, the earth is absorbed by the earth’s surface, which, causes an increase in the temperature of the earth’s, surface. Some heat is also trapped by green house, gases, ie. carbon dioxide, methane, nitrous oxide,, zone, chloro-fluoro-carbon compounds (CFC) and, water vapour present in the atmosphere. This, causes GLOBAL WARMING., , 84, , , , , , $4.1 Green house effect, , , , Heating of the earth and its environment due to, olar radiation trapped by greenhouse gases such, as carbon dioxide and water vapour in the, atmosphere is called greenhouse effect., , , , , , , , Industrial processes like manufacture of lime, and those seen in fermentation units., Biological decay of plan, , , , Respiration by animals, human beings and, plants., , Water vapours, , The main source of water vapour is burning, , of hydrocarbons. This produces carbon dioxide and, water vapour,, , Hydrocarbon + Oxygen —> Carbon dioxide + Water vapour, , Oxides of Nitrogen, , Combustion of fossil fuels like coal, oil,, natural gas, gasoline, etc. in automobiles and power, plants produce high temperatures, whereupon, , , , , , , , , , , , , , , , , , , , , , , , , , nitrogen and oxygen combines to form nitric oxide, and nitrogen dioxide. Some chemical industries, also produce oxides of nitrogen as by-products., , , , |The name green house comes from glass, | structures called green houses that are used to, grow green plants in the colder regions of the, earth. The glass structure allows sunlight to, enter it but does not allow the radiated heat to, escape, thus heating up the green house., , , , , , Met!, , , , It is emitted in large quantities during, anaerobic decomposition of organic matter in soil,, water and sediments. Incomplete combustion of, fossil fuels also produces methane and other, hydrocarbons., , , , 84.2, , Gases that contribute to greenhouse effect are, carbon dioxide, water vapour, oxides of nitrogen,, methane, ozone, chloro-fluro-carbons, etc., and are, thus called greenhouse gases. The relative, Contributions of these gases towards greenhouse, tffect is given in the following table :, , Greenhouse gases :, , Mechanism of Greenhouse effect, , Sunlight reaching the earth consists of three, types of radiations, namely, ultraviolet (UV), radiation, visible radiation and infra-red (IR), radiation. As sunlight passes through the, atmosphere, most of the UV radiation is absorbed, by ozone; 30% of IR radiation reaches the earth's, surface, heating up th Ae the ah, , , , , , , , , , , Sources of greenhouse, S804 7, ves of greenhouse gases are :, & r, ‘Arbon dioxide, , Buming of fossil fuels like, id Petroleum., , , , , , glaciers and polar ice caps have staneg, , , , : and gradually this may lead to ay ‘age Mey, | an sea level. This will in turn flood Several « :, areas in countries like India, Bang, , 60, Netherlands and Maldives. sradey,, , ¢ Global warming will cause more Wat, evaporate from water bodies, thus forming” b, water vapour. Since water vapour, contributes to greenhouse effect a, warming will further incre: * 8toby,, , nS, ‘The Earth emits heat energy in the form of, infrared rays,, ‘The sun's energy is absorbed by the Earth, , , , , e Global warming can lead to chanc..