As we have seen, scientists have grown progressively more worried about the potential for climate change caused by increasing atmospheric carbon dioxide levels. The world burns the fossil fuel equivalent of approximately 9.0 × 1012 kg of petroleum per year. Assume that all of this petroleum is in the form of octane (C8H18) and calculate how much CO2 in kilograms is produced by world fossil fuel combustion per year. (Hint: Begin by writing a balanced equation for the combustion of octane.) If the atmosphere currently contains approximately 3.0 × 1015kg of CO2, how long will it take for the world's fossil fuel combustion to double the amount of atmospheric carbon dioxide?
From the above data, we can write the following chemical equation for combustion of octane,
C8H18 + 25/2 O2 8 CO2 + 9 H2O
Mass of CO2 produced = 9.0 × 1012 kg of C8H18 (1mol of C8H18/114 g of C8H18) (8 mol of CO2/1 mol of C8H18) (44g of CO2/1 mol of CO2)
= 2.8 10 13 kg of CO2
Present mass CO2 in atmosphere = 3.0 × 1015 kg of CO2
Time taken to produce same amount = 3.0 × 1015 kg of CO2 /2.8 10 13 kg of CO2
= 107 years.