In atmospheric air, the share of nitrogen is n = 0.76 mass, and the share of oxygen is n = 0.24

In atmospheric air, the share of nitrogen is n = 0.76 mass, and the share of oxygen is n = 0.24 (if we neglect the impurities of other gases). Calculate the average molar mass of air.

To find the value of the average molar mass of air for the given conditions, we use the equality: mN2 / MN2 + mO2 / MO2 = m / mair.

Constants and variables: mN2 (nitrogen fraction) = 0.76m; MN2 is the molar mass of nitrogen (MN2 = 28 g / mol); mO2 (oxygen fraction) = 0.24m; MO2 is the molar mass of oxygen (MO2 = 32 g / mol).

Let’s calculate: 0.76m / 28 + 0.24m / 32 = m / mair.

0.76 / 28 + 0.24 / 32 = 1 / mair

mair = 28 * 32 / (0.76 * 32 + 0.24 * 28) = 896 / 31.04 = 28.87 g / mol.

Answer: The molar mass of air, according to the calculation, is 28.87 g / mol.