Calculate the relative plane of hydrogen bromide in air.

Given:
hydrogen bromide – HBr

To find:
D air. (HBr) -?

Decision:
The relative density of one gas in another (D) is the ratio of the molar mass of a given gas to the molar mass of the gas in which it is located.
1) Using the periodic system of D.I.Mendeleev, calculate the molar mass of HBr, which will be numerically equal to the molecular mass:
Mr (HBr) = Ar (HBr) + Ar (HBr) = 1 + 80 = 81 g / mol;
2) Calculate the relative density of hydrogen bromide in air:
D air. (HBr) = Mr (HBr) / Mr (air) = 81/29 = 2.79.

Answer: The relative density of HBr in air is 2.79.