1. The problem statement, all variables and given/known data The world burns approximately 3.8 x 1012 kg of fossil fuel per year. 1. Use the combustion of octane as the representative reaction and determine the mass of carbon dioxide (the most significant greenhouse gas) formed per year. 2. The current concentration of carbon dioxide in the atmosphere is approximately 368 ppm (by volume). By what percentage does the concentration increase each year due to fossil fuel combustion? Approximate the average properties of the entire atmosphere by assuming that the atmosphere extends from sea level to 15 km and that it has an average pressure of 381 torr and average temperature of 275 K. Assume Earth is a perfect sphere with a radius of 6371 km. 2. Relevant equations Volume of a sphere = (4/3)π(r3) Percent change = (new - old)/old * 100 3. The attempt at a solution I already calculated #1. 1. 1.2 x 10^6 g 2. Vatm = Vearth+atmosphere - Vearth Vatm = (4/3)π(63863 - 63713) = 7.66899 x 109 km3 = 7.66899 x 1018 m3 368 ppm = 368 g/m3 Using mass obtained from #1, and finding concentration of the increase in CO2: 1.2 x 1016g/7.66899 x 1018 m3 = 0.001564743 g/m3 New concentration = 368 + 0.001564743 Percent change = (new-old)/old * 100 = 0.00042519% So the answer is 0.42%, and it seems that the way to achieve this is to have the Vatm = 7.66899 x 1015 m3 rather than 7.66899 x 1018 m3. Is there an error in my volume calculation that I am not catching?