1. The problem statement, all variables and given/known data one mole of an ideal gas takes up 0.0225m3 at 0 degrees celsius and 1.01x10(5) pascals. (calculated) hence, calculate the volume of 1 mole of air (ideal) at an altitude of 15km above sea level. average molecular mass of air = 29 amu. T @ altitude of 15km = 0 degrees C. 2. Relevant equations I used pv=nrt for the first part. another equation i can find is M = m N A where M is the mass of the mole in kg, m is the atomic mass unit in kg, N is the atomic mass, and A is avogadros constant. 3. The attempt at a solution volume of a mole of air can be calculated using pv=nrt, rearranged for v which is v=nrt/p. however, i have no idea how to bring the altitude into it! thanks for help! Edit: Perhaps equation P = P0 exp (-mgy/k(b) t)? where m = average molecular mass in kg, g = acceleration due to gravity, y = altitude in m, kb is boltzmanns constant and t is temperature? but i'm not sure where to find volume.