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is the molecular mass of dry air, approximately 4.81 × 10 −26 in kg. [note 1], the specific gas constant for dry air, which using the values presented above would be approximately 287.050 0676 in J⋅kg −1 ⋅K −1. [note 1] Therefore:
Water vapor and dry air density calculations at 0 °C: The molar mass of water is 18.02 g/mol, as calculated from the sum of the atomic masses of its constituent atoms. The average molar mass of air (approx. 78% nitrogen, N 2; 21% oxygen, O 2; 1% other gases) is 28.57 g/mol at standard temperature and pressure .
Molecular weight (M.W.) (for molecular compounds) and formula weight (F.W.) (for non-molecular compounds), are older terms for what is now more correctly called the relative molar mass (M r). [8] This is a dimensionless quantity (i.e., a pure number, without units) equal to the molar mass divided by the molar mass constant .
The molecular mass (m) ... water has a molar mass of 18.0153(3) ... A Free Android application for molecular and reciprocal weight calculation of any chemical formula;
= molecular weight of the air pollutant ... calculate the equivalent ... a wet basis concentration of 40 ppmv in a gas having 10 volume percent water vapor would have ...
Air is given a vapour density of one. For this use, air has a molecular weight of 28.97 atomic mass units, and all other gas and vapour molecular weights are divided by this number to derive their vapour density. [2] For example, acetone has a vapour density of 2 [3] in relation to air. That means acetone vapour is twice as heavy as air.
The gaseous state of water is lighter than air (density 0.804 g/L at STP, average molecular mass 18.015 g/mol) due to water's low molar mass when compared with typical atmospheric gases such as nitrogen gas (N 2). It is non-flammable and much cheaper than helium. The concept of using steam for lifting is therefore already 200 years old.
= latent heat of water vaporization, 2.45 [MJ kg −1], = specific heat of air at constant pressure, [MJ kg −1 °C −1], = ratio molecular weight of water vapor/dry air = 0.622. Both and are constants.