1. The problem statement, all variables and given/known data 1. Ozone has a maximum concentration of 4.7 x 1012 molecules/ cm3 at an altitude of 20 km. The total pressure at this altitude is 100 torr. Using the ideal gas law, what is the mole fraction of O3 at that altitude? Now express the mole fraction in ppb. 2. Relevant equations PV=nRT (ideal gas law) X/(X_a + X_b...) mole fraction temperature @ 20 km = -50 Celsius = 223 K 100 torr = .132 atm 3. The attempt at a solution So far I have taken concentration of ozone and put it into mol/L. 4.7 x 10^12 molecules/cm^3 = 7.81 x 10^-9 mol/L I'm not sure how to find a mole fraction without additional information. All the info for ideal gas law is also all there so I'm confused. I forgot how to take mol/L into just moles I guess. I've looked online for more information and reading up on the general chemistry but am unable to find any information related to this problem. Also notable is the fact that I do not have a general chemistry textbook (my brother sold it for money) which would ideally give me a refresher in PV= nRT and finding the solution to this problem. So, any help would be appreciated.