Question

Step 1: If CO2 in oceans were to rise from 300 ppm to 400 ppm (parts per million - I get a conversion here of 6.8 mM to 9.1 mM) and oceans represent a volume of 1.335 X 1021 L, how many moles of CO2 is that in the ocean for 300ppm (6.8 mM) and for 400ppm (9.1mM)?

Step 2: We often talk in "billions of barrels of oil" when we discuss yearly consumption rates. Assuming that a billion barrels of oil are equivalent to about 1.5 X1014 g of oil - and let's just simplify the chemical makeup of "oil" to be all octane (C8H18). If we added the carbon from 1.5 X1014 g of octane straight to the oceans (that isn't how it works really...), how much would we increase that 9.1 mM concentration above?

need help with this one >Step3: This gets into Le Chatelier's principle and into the buffering concepts of chapter 10. If the ocean starts at pH 7 (it isn't - it is really a good bit higher): calculate the concentrations of [H+], [H2CO3] and [HCO3-] in each of the three concentration scenarios you have above. The way I recommend approaching this is to calculate the pH based on the 6.8mM concentration and then use the Henderson-Hasselbach equation to find what happens when you shift the concentrations - remember that pKa is a constant and does not change (at least in Introductory Chemistry).