Answers to questions on Environmental impact - global warming

1. (a) Water or ozone (or other CFCs)

(b) Since 1750 the industrial revolution has taken place and the use of fossil fuels (which produce carbon dioxide when burned) for energy, industry and transport has increased hugely. As the population has increased emissions of methane have increased due to
increased farming and the release of natural gas.

(c) CFCs (used in aerosols and refrigerants and first made in the 1890s) and sulfur hexafluoride (used as an electrical insulator and first made in 1901) are both man made and do not occur naturally.

(d) Sulfur hexafluoride is the most potent greenhouse gas. Even a small increase in its concentration in the atmosphere could lead to a significant increase in global warming.

2. (a) The eight shared electrons in the two double C=O bonds around the central carbon atom act as two electron domains so the basic shape is linear with a bond angle of 180^o.

(b) Higher energy incoming light from the sun passes through the molecules of carbon dioxide. The lower energy infrared light radiated back from the Earth is absorbed by the stretching and bending bond vibrations of the carbon dioxide molecules as a change in dipole moment takes place. This prevents much of the heat escaping from the atmosphere as it is re-radiated back to the earth.

(c) There is an equilibrium between the carbon dioxide in the atmosphere and the carbon dioxide dissolved in seawater. Carbon dioxide in water dissolves to form carbonic acid (H₂CO₃) so as the concentration in the seawater increases the seawater becomes more acidic. The increased concentration of hydrogen ions causes more of the coral (which is mainly CaCO₃) to react to form calcium ions, carbon dioxide and water.

(d) Reduce energy consumption and increase energy efficiency.
Switch from fossil fuels to non-carbon sources of energy such as wind power, nuclear energy, solar energy and geothermal energy. and sustainable sources of energy.
Prevent carbon dioxide from entering the atmosphere when fossil fuels are combusted by carbon capture and sequestration

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