Consequences of using fossil fuels Wong Yu Tso Yat Long Wong Mei Sze Ho Kin Fung

Consequences of using fossil fuels Fossil fuels create environmental problems resulting from: Extraction and processing Transportation and storage Combustion

Air pollution Major sources of air pollutants are: Exhaust of motor vehicles Power plants Factories Incinerators

Air pollution Main air pollutants include: Carbon monoxide, forms when fossil fuels are burnt incompletely. CxHy + O2  CO2 + H2O + CO + C Sulphur dioxide, most fossil fuels contain sulphur. When they are burnt, they give out sulphur dioxide. [S] + SO2  CO2 Nitrogen oxides, include nitrogen monoxide and nitrogen dioxide, produced when fossil fuels are burnt at high temperature.

Air pollution Unburnt hydrocarbons, from motor vehicles, it irritate our respiratory system. Suspended particulates, small solid particles that remain suspended in air for a long time.

Acid rain Rainwater is naturally acidic, with a pH of about 5.6. This is because CO2 in the air dissolves in rainwater to form carbonic acid. CO2 + H2O  H2CO3 However, Rainwater with pH less than 5.6 is called acid rain, because sulphur dioxide and nitrogen oxides dissolve in rainwater to form sulphurous acid and nitrous acid. SO2 + H2O  H2SO3 Some acids further reacts with oxygen to form sulphuric acid and nitric acid. H2SO3 + [O]  H2SO4

Harmful effects of acid rain Damaging plants, acid rain make the soil acidic, many plants cannot grow well in acidic soil. Also, leaves are damaged by acid, plants will die as photosynthesis cannot take place. Killing aquatic life, Fish and water plants cannnot survive in water which is too acidic.

Corroding metal objects, metal fences, bridges and car bodies, even underground metal pipelines, will be corroded by acid rain. Fe + 2H+  Fe2+ + H2 Corroding building materials, acid rain will corrode materials including limestone, marble, sandstone, cement and concrete. The calcium carbonate in these materials will be dissolved by acid. CaCO3 + 2H+  Ca2+ + CO2 + H2O

Possible ways to reduce the formation of acid rain To control acid rain, we must reduce the emission of acidic pollutants. Possible ways are: Installing catalytic converters in motor vehicles Using LPG instead of diesel oil Using fuels of low sulphur content in factories Using scrubbers and flue gas desulphurization system