# An Easy Explanation of How to Calculate the Molar Mass of Air

The molar mass of a compound is the smallest measurable mass of that compound. Air is a mixture of various constituent gases.

ScienceStruck Staff

Last Updated: Apr 28, 2018

Did You Know?

The molar mass of a hydrogen molecule (H

_{2}) is the lowest among all compounds under normal conditions.Thus, it is defined as,

Molar Mass

**Molar Mass = (Mass of the Substance)/(Amount of the Substance)**

Molar Mass of a Mixture

So how to calculate the molar mass of air, which is composed of various gases in different proportions? Air is a mixture, and the formula to obtain the average molar mass of a mixture is as given below,

M = ∑a

Here,

M = Molar Mass

a

Y

M = ∑a

_{i}× Y_{i}Here,

M = Molar Mass

a

_{i}= Fraction of the Constituent 'i'Y

_{i}= Molar Mass of the Constituent 'i'^{-8}fractions (9 × 10

^{-6}%) of xenon.

The steps for the calculation of molar mass of an element have been given here. The molar mass of constituent elements of air is as follows,

Molar Mass of Constituents

- Nitrogen = 28 g/mol
- Oxygen = 32 g/mol
- Argon = 40 g/mol
- Carbon Dioxide = 44 g/mol
- Neon = 20 g/mol
- Helium = 4 g/mol
- Krypton = 83.8 g/mol
- Hydrogen = 2 g/mol
- Xenon = 131.29 g/mol

Molar Mass of Air

M | = | (0.7808 × 28) + (0.2095 × 32) + (0.00933 × 40) + (0.0003 × 44) + (0.000018 × 20) + (0.000005 × 4) +(0.000001 × 83.8) + (0.0000005 × 2.02) +(9 × 10^{-8} × 131.29) |

= | 21.86 + 6.704 + 0.373 + 0.013 + 0 + 0 + 0 + 0 + 0 | |

= | 28.96 |

Hence, the molar mass of dry air is 28.96 g/mol.