1. Car Exhaust Gases What are the origins and environmental implications of pollutants in car exhaust gases?

2. The Six Pollutants unburnt hydrocarbons carbon monoxide particulates carbon dioxide nitrogen oxides (NO x ) sulphur dioxide

3. Unburnt Hydrocarbons Hydrocarbons>>> Compounds of hydrogen and carbon with the general formal C x H y Sometimes not all the hydrocarbons are burnt completely e.g. the spark plug ignites some fuel air mixture This can have serious effects on the environment Carcinogenic, highly flammable, photochemical smog

4. Carbon Monoxide (CO) Produced in incomplete combustion of hydrocarbon fuels: C 3 H 8 + 5O 2  3CO 2 + 4H 2 O 2C 3 H 8 + 7O 2  2C + 2CO +8H 2 O+2CO 2 Complete Combustion of Propane: Incomplete Combustion of Propane: Harmful Effects: very toxic to humans oxidised to CO 2 in the atmosphere one of the primary pollutants of photochemical smog produces particulates

5. Particulates They are very small carbon (C) particles Produced mainly by incomplete combustion Cause many health problems Fog – contribute to photochemical smog

6. Carbon Dioxide (CO 2 ) Combustion (burning of the fuel) will produce carbon dioxide Hydrocarbon (fuel) + Oxygen  Carbon Dioxide + Water CO 2 is released into the atmosphere Traps in heat energy from the sun  greenhouse effect  contributes to global warming

7. Nitrogen Oxides (NO x ) Nitrogen oxides are emitted by vehicle exhausts (NO and NO 2  NO x ) PHOTOCHEMICAL FOG Secondary pollutants Primary pollutants OZONE SMOG (contributes to ozone smog) Effects human health – especially those venerable such as asthmatics and the elderly Acid Rain

8. Sulphur Dioxide (SO 2 ) Sulphur dioxide is present in car exhaust fumes, though it is in the minority. Sulphur Compounds in the fuel + air (O 2 ) >>> Sulphur dioxide Acid Rain: Nitrogen oxides and sulphur oxides form acids easily (nitric and sulphuric acid). The rain washes these acids out of the air to form acid rain. Destroys stone buildings Corrosion (iron and steel) Forests and lakes

9. Photochemical Smog Primary Pollutants Secondary Pollutants (not released directly into atmosphere) NO x, C x H y, CO O 3 (ozone), NO 2, H 2 O 2, PAN (peroxyacetyl nitrate), HNO 3 and partially oxidised hydrocarbons Ozone (O 3 ) is the main constituent and causes many of the health problems related to the smog. Ozone is formed when sunlight shines on a mixture of 2 primary pollutants.