Combined ScienceCode 5129
Air quality and climate
What this topic asks you to be able to do
- Give the make-up of clean, dry air: about 78% nitrogen, N2, and 21% oxygen, O2, with the balance being noble gases plus carbon dioxide, CO2
- State where each of these air pollutants comes from: (a) carbon dioxide – complete combustion of fuels that contain carbon (b) carbon monoxide and particulates – incomplete combustion of fuels that contain carbon (c) methane – decomposition of vegetation, and the waste gases animals produce during digestion (d) gases – given off when plastics are burned
- State the harmful effect of each of these air pollutants: (a) carbon dioxide – more of it in the air increases global warming, and this causes climate change (b) carbon monoxide – a toxic gas (c) particulates – a greater risk of cancer and respiratory problems (d) methane – more of it in the air increases global warming, and this causes climate change (e) gases from burning plastics – toxic
- State and explain ways of reducing global warming, limited to: using more renewable energy, using fewer fossil fuels, limiting deforestation and reducing livestock farming
- State that a hydrogen–oxygen fuel cell generates electricity from hydrogen and oxygen; water is the only chemical product it yields
- Describe how hydrogen–oxygen fuel cells compare with gasoline/petrol engines as a way to power vehicles, giving their advantages and disadvantages