If we were to increase atmospheric CO2 fivefold by the burning of fossil fuels, how much would the atmospheric oxygen concentration change relative to what it is today? Assume: (a) CO2 concentration today is 400 ppm, (b) the atmosphere today is made of 21% oxygen, and (c) the burning of fossil fuels consumes 1.4 moles of O2 per mole of CO2 produced
To calculate the change in atmospheric oxygen concentration, we need to consider the stoichiometry of the combustion reaction that converts oxygen (O2) to carbon dioxide (CO2) during the burning of fossil fuels.
Given that the burning of fossil fuels consumes 1.4 moles of O2 per mole of CO2 produced, we can use this information to calculate the number of moles of oxygen consumed when the CO2 concentration increases fivefold:
1. Calculate the moles of CO2 in the current atmosphere:
CO2 concentration today = 400 ppm (parts per million) = 400/1,000,000 = 0.0004 (moles of CO2 per mole of air)
2. Multiply the moles of CO2 in the current atmosphere by five to determine the future concentration:
Future CO2 concentration = 5 * 0.0004 = 0.002 (moles of CO2 per mole of air)
3. Determine the moles of O2 consumed per mole of CO2 produced:
Moles of O2 consumed = 1.4 (moles of O2 per mole of CO2)
4. Multiply the future CO2 concentration by the moles of O2 consumed per mole of CO2:
Moles of O2 consumed in the future = 0.002 * 1.4 = 0.0028 (moles of O2 per mole of air)
5. Calculate the change in moles of O2 relative to what it is today:
Change in moles of O2 = Moles of O2 consumed in the future - Moles of O2 consumed today
Since the current atmospheric composition is 21% oxygen, or 0.21 moles of O2 per mole of air, we can proceed with the calculations:
Change in moles of O2 = 0.0028 - 0.21 = -0.2072 (moles of O2 per mole of air)
Therefore, the atmospheric oxygen concentration would decrease by 0.2072 moles per mole of air if atmospheric CO2 were to increase fivefold through the burning of fossil fuels.