Chapter 10: Chemistry of the environment
Tests for presence of water (2)
Anhydrous copper(II) sulfate changes from white to blue when water is added.
Cobalt(II) chloride paper turns pink if water is present.
Test for purity of water
Sharp boiling point at 100, sharp melting point at 0.
Treatment of domestic water supply.
1) Sedimentation and filtration to remove solids
2) Use of carbon to remove tastes and odours
3) Chlorination to kill microbes
Clean dry air composition
78% Nitrogen
21% Oxygen
Remainder is CO2 and other noble gases.
Carbon Dioxide
- Complete combustion of carbon containing fuels
- Higher levels of CO2 lead to increased global warming and climate change
Carbon Monoxide and particulates
- Incomplete combustion of carbon containing fuels
- Toxic gas and the particulates increase risk of respiratory problems and cancer
Methane
- Decomposition of vegetation and waste gases from digestion in animals
- High levels of methane increases global warming and climate change
Oxides of Nitrogen
- From car engines
- Acid rain, photochemical smog, respiratory problems
Sulfur Dioxide
- Combustion of fossil fuels containing sulfur compounds
- Acid rain
How do CH4 and CO2 cause global warming
- Absorption of thermal emergy from the sun by the Earth heats up the Earth.
- Remainder of energy is reflected back into space
- Earth radiates some energy back into space but the greenhouse gases prevent it from escaping and reduce the thermal energy loss to space
Ways to reduce the effect of climate change
- Planting trees
- Reduction in livestock farming
- Decreasing use of fossil fuels
- Increasing use of renewable energy
Ways to reduce acid rain
- Catalytic converters : 2CO + 2NO -> 2CO2 + N2
- Use low sulfur fuels
Photosynthesis
carbon dioxide + water -> (chlorophyll + light) -> glucose + oxygen
6CO2 + 6H2O -> C6H12O6 + 6O2