Chapter 14 Environmental Chemistry Solutions
Question - 1 : - Define environmental chemistry?
Answer - 1 : -
Environmental Chemistry is thebranch of science which deals with the chemical changes in the environment. Itincludes our surroundings such as air, water, soil, forest etc.
Question - 2 : - Explain the tropospheric pollution in 100 words?
Answer - 2 : -
Tropospheric pollution occurs due tothe presence of undesirable substance in air. These may be the solid or gaseouspollutants.
· GaseousAir Pollutants: These are oxides of sulphur,nitrogen and carbon, hydrogen sulphide, hydrocarbons, ozone and other oxidants.
· ParticulatePollutants: These are dust, mist, fumes,and smog etc.
Question - 3 : - Carbon monoxide gas is more dangerous than carbon dioxide gas. Why?
Answer - 3 : -
Carbon monoxide combines withhaemoglobin to form a very stable compound known as carboxyhaemoglobin when itsconcentration in blood reaches 3-4%, the oxygen carrying capacity of the bloodis greatly reduced. This results into headache, nervousness and sometimes deathof the person. On the other hand CO2 does not combine withhaemoglobin and hence is less harmful than CO.
Question - 4 : - Which gases are responsible for greenhouse effect? List some of them.
Answer - 4 : -
CO2 is mainlyresponsible for greenhouse effect. Other greenhouse gases are methane, nitrousoxide, water vapours, CFCs and Ozone.
Question - 5 : - Statues and monuments in India are affected by acid rain. How?
Answer - 5 : -
This is mainly due to the largenumber of industries and power plants in the nearby areas. Acid rain hasvapours of sulphuric acid dissolved in it. When it comes in contact withvarious statues or monuments, the acid reacts chemically with calciumcarbonate.
CaCO3 + H2SO4 ——–> CaSO4 +H2O + CO2
Question - 6 : - What is smog? How is classical smog different from photochemical smog?
Answer - 6 : - Theword smog is a combination of smoke and fog. It is a type of air pollution thatoccurs in many cities throughout the world. Classical smog occurs in cool humidclimate. It is also called as reducing smog.Whereas photochemical smog occursin warm and dry sunny climate. It has high concentration of oxidising agentsand therefore, it is also called as oxidising smog.
Question - 7 : - Write down the reactions involved during the formation of photochemical smog.
Answer - 7 : - Mechanism of formation of photochemical smog:
Question - 8 : - What are the harmful effects of photochemical smog and how can they be controlled?
Answer - 8 : -
Harmfuleffects of photochemical smog:
· Their’high concentration causesheadache, chest pain and dryness of the throat.
· Ozone and PAN act as powerful eyeirritants.
· Photochemical smog leads to crackingof rubber and extensive damage to plant life.
· It causes corrosion of metals,stones, building materials, and painted surface etc.
Control:
· Use of catalytic converter inautomobiles prevents the release of nitrogen dioxide and hydrocarbons to theatmosphere.
· Pinus, juniparus, quercus, pyrusetc. can metabolise nitrogen dioxide thus their plantation could help to someextent.
Question - 9 : - What are the reactions involved for ozone layer depletion in the stratosphere?
Answer - 9 : -
The reaction can be shown asfollows:
CF2Cl2(g) + UV ——-> Cl(g) + CF2Cl(g)
Cl(g) + O3(g) ———-> ClO (g) + O2(g)
ClO(g) + O(g) ———> Cl + O2(g)
Question - 10 : - What do you mean by ozone hole? What are its consequences?
Answer - 10 : -
Depletion of ozone layer creates some sort of holes in the blanket of ozone which
surround us, this is known as ozone hole.
• With the depletion of the ozone layer, UV radiation filters into the troposphere which leads to aging of skin, cataract, sunburn, skin cancer etc.
• By killing many of the phytoplanktons, it can damage the fish productivity.
• Evaporation rate increases through the surface and stomata of leaves which can decrease the moisture content of the soil.