Question

Find the molar mass of the air:

atomic molar masses and %

Oxigen: 1.5944 21%

Nitrogen: 1.40067 78%

Argon: 3.9948 1%

If you can write steo by step I would really appreciate it, and it would help me to understand.

Answer 1

Solution:

Calculation of Molar mass of Air:

Air contains: O2 = 21 % , N2 = 78 % and Ar = 1 %

The molecular weights of O2,N2 and atomic weight of Ar are calculated from their atomic masses as,

Nitrogen (N2) =  14.0067 x 2 = 28.0134 g/mol
Oxygen (O2)= 15.944 x 2 = 31.888 g/mol
Argon (Ar) = 1 x 39.948 = 39.948 g/mol

Thus, molar masses of O2, N2 and Ar in Air is calculated as,

N2 = (78 / 100) x 28.0134 = 21.85045 g/mol
O2 = (21 / 100) x 31.888 = 6.69648 g/mol
Ar =  (1 / 100) x 39.948 = 0.39948 g/mol

If we add these values, we obtained the molar mass of air =21.85045 + 6.69648 + 0.39948 = 28.946 g / mol

Thus, molar mass of air = 28.946 g /mol