Name the gasecous pollutants present in the air and explain their formation.

Explanation

Gaseous pollutants present in air are .
a) Oxides of sulphur .
b) Oxides of nitrogen
c) Oxides of carbon
d) Hydrocarbons
a) Oxides of sulphur :
`to` The oxides of sulphur formed by the fossil fuel containing sulphur are burnt.
`S + O_(2) to SO_(2)`
`to` Sulphur diokide oxidises to form sulphur trioxide in presence of catalyst.
`2SO_(2) + O_(2) hArr 2SO_(3)`
`to` Sulphur trioxide can also be formed by the reaction of `SO_(2)`, with `O_(3)`, (or) `H_(2)O_(2)` .
`SO_(2) + O_(3) hArr SO_(3) + O_(2)`
`SO_(2) + H_(2)O_(2) to H_(2)SO_(4)`
`to SO_(2)` is the most common oxide and causes the following adverse effects.
(a) It causes respiratory problems like asthma, bronchitis etc.
b) It is poisonous to both animals and plants.
c) It causes irritation to the eyes which results in tears and redness.
(b) Oxides of nitrogen :
`to` The major gases present in air are oxygen and nitrogen .
`to` These donot combine at normal temperature.
`to` Dinitrogen and dioxygen combined at high altitudes in presence of light to from oxides of nitrogen .
`N_(2(g)) + O_(2(g)) overset(1483K)to 2NO_((g))` .
`to` No reacts with oxygen to from `NO_(2)`
`to NO_(2) ` is quickly formed by the reaction of NO with `O_(3)` .
`NO + O_(3) to NO_(2) + O_(2)`
Adverse Effects :-
`to NO_(2)` damages the leaves of plants and effects the efficiency of photosynthesis.
`to NO_(2)` cause lung problems.
`to NO_(2)` causes respiratory problems.
`to NO_(2)` affects the textile fibers and metals.
(c) Oxides of carbon :
(i) Carbon monoxide (CO) : -
`to` CO is one of the most harmful air pollutants.
`to CO` gas is produced by the incomplete combustion of carbon (coal, firewood , petrol etc) `C_((s)) + (1)/(2)O_(2_(g)) to CO_((g))`
`to CO` is mainly relased into atmosphere by automobiles.
Adverse effects :
`to` It stops the transportation of oxygen to the organs and tissuess.
`to` When it is inhaled by a human being it froms stable complex with haemoglobin of blood. This complex is named as carboxy haemoglobin.
`CO + Hb to CO - Hb`
`to` This reduces the oxygen transportant in body and results into headache , eye problems , nerveous problems and heart problems and heart problems .
(ii) Carbondioxide :
`to CO_(2)` is entered into atmosphere mainly by respiration process.
`to CO_(2)` si also formed by the burning of fossil fuels .
`C + O_(2) to CO_(2) ` + heat energy .
`to CO_(2)` is formed by the decomposition of lime stone .
`CaCO_(3) overset(Delt) to CaO + CO_(2)`
Effects :
`to ` Due to deforestion and buring of fossil fuels increase `CO_(2)` release and the balance `O_(2) - CO_(2)` in atmosphere disturbed .
`to` The increased level of `CO_(2)` cause global warming which cause serveral problems like dengue, malaria etc.
`to` Due to global warming effciency of photosynthesis decrease.
(d) Hydrocarbons :
`to` These mainly constitues hydrogen and carbon .
`to` These manly constitutes hydrogen and carbon.
`to` These are formed by the incomplete combustion of fuel used in auto mobiles .
Adverse Effects :
`to` These cause cancer.
`to` These are harmful to plants causing ageing break donw of tissues, flowers and leaves are shedded.