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10. Chemistry of the environment

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  1. 10.1 Water

    1. 10.1.1Chemical tests for the presence of

      • Describe chemical tests for the presence of water using anhydrous cobalt(II) chloride and anhydrous copper(II) sulfate

    2. 10.1.2To test for the purity of water using

      • Describe how to test for the purity of water using melting point and boiling point

    3. 10.1.3Distilled water is used in practical

      • Explain that distilled water is used in practical chemistry rather than tap water because it contains fewer chemical impurities

    4. 10.1.4Substances found in natural water

      • State substances found in natural water: dissolved oxygen, metal compounds, plastics, sewage, harmful microbes, fertiliser nitrates, and phosphates from fertilisers/detergents

    5. 10.1.5Some of these substances are

      • State: some of these substances are beneficial, (a) dissolved oxygen for aquatic life (b) some metal compounds provide essential minerals for life

    6. 10.1.6Harmful substances: toxic metal

      • State harmful substances: toxic metal compounds, plastics harming aquatic life, sewage microbes causing disease, and nitrates/phosphates causing deoxygenation and aquatic damage. Eutrophication details not required

    7. 10.1.7Treatment of the domestic water supply

      • Describe treatment of the domestic water supply in terms of: (a) sedimentation and filtration to remove solids (b) use of carbon to remove tastes and odours (c) chlorination to kill microbes

  2. 10.2 Fertilisers

    1. 10.2.1Ammonium salts and nitrates are used

      • State: ammonium salts and nitrates are used as fertilisers

    2. 10.2.2Use of NPK fertilisers to provide the

      • Describe use of NPK fertilisers to provide the elements nitrogen, phosphorus and potassium for improved plant growth

  3. 10.3 Air quality and climate

    1. 10.3.1Composition of clean, dry air as

      • State the composition of clean, dry air as approximately 78% nitrogen, N2, 21% oxygen, O2 and the remainder as a mixture of noble gases and carbon dioxide, CO2

    2. 10.3.2Air pollutant sources: CO2 from

      • State air pollutant sources: CO2 from complete combustion; CO/particulates from incomplete combustion; methane from decomposing vegetation and animal digestion; nitrogen oxides from car engines; sulfur dioxide from sulfur-containing fossil fuels

    3. 10.3.3Pollutant effects: CO2 and methane

      • State pollutant effects: CO2 and methane increase global warming/climate change; CO is toxic; particulates increase respiratory/cancer risk; nitrogen oxides cause acid rain, photochemical smog and respiratory problems; sulfur dioxide causes acid rain

    4. 10.3.7Greenhouse gases carbon dioxide and

      • Describe how the greenhouse gases carbon dioxide and methane cause global warming, (a) the absorption, reflection and emission of thermal energy (b) reducing thermal energy loss to space

    5. 10.3.4Reduction strategies: for climate

      • Explain reduction strategies: for climate change, plant trees, reduce livestock, use less fossil fuel, increase hydrogen/renewables; for acid rain, use catalytic converters, low-sulfur fuels and flue gas desulfurisation with calcium oxide

    6. 10.3.5Photosynthesis as the reaction between

      • Describe photosynthesis as the reaction between carbon dioxide and water to produce glucose and oxygen in the presence of chlorophyll and using energy from light

    7. 10.3.6Word equation for photosynthesis

      • State the word equation for photosynthesis, carbon dioxide + water → glucose + oxygen

    8. 10.3.8How oxides of nitrogen form in car

      • Explain how oxides of nitrogen form in car engines and describe their removal by catalytic converters, e.g. 2CO + 2NO → 2CO2 + N2

    9. 10.3.9Symbol equation for photosynthesis

      • State the symbol equation for photosynthesis, 6CO2 + 6H2O → C6H12O6 + 6O2