Calculate the total mass of methane (CH_4) that would need to be added to the atmosphere to increase the atmospheric concentration by 1 ppm on Earth. The total mass of the atmosphere is 5.12 times 10^21 grams, the density of air is 1291.8 g/m^3, and 44.91 mol of gas occupies 1 m5 at standard temperature and pressure. Solution total volume of air= 5.12*1021 /1291.8=3.9635*1018 m3 volume of methane required= 1/106 *3.9635*1018 = 3.9635*1012 m3 = 3.9635*1012 *44.91 mole =188*1012 mole 1 mole= 16 g =16*10-6 ton total mass = 188*1012 *16*10-6 = 2.85 *109 ton.