How do you find the density of air? Can you please explain and give me two examples (1 that is already answered and the other example is blank this way I try it for myself). Thank you for your time!
Answers
Answer:
The most basic and straightforward air density formula is simply dividing the mass of air by its volume. This is the standard definition of density as
\rho = \frac{m}{V}ρ=
V
m
for density ρ ("rho") generally in kg/m3, mass m in kg and volume V in m3. For example, if you had 100 kg of air that took up a volume of 1 m3, the density would be 100 kg/m3
Explanation:
To get a better idea of the density of air specifically, you need to account for how air is made of different gases when formulating its density. At a constant temperature, pressure and volume, dry air is typically made of 78% nitrogen (N2), 21% oxygen (O2) and one percent argon (Ar).
To take into account the effect that these molecules have on air pressure, you can calculate the mass of air as the sum of nitrogen's two atoms of 14 atomic units each, oxygen's two atoms of 16 atomic units each and argon's single atom of 18 atomic units.
If the air isn't completely dry, you can also add some water molecules (H2O) which are two atomic units for the two hydrogen atoms and 16 atomic units for the singular oxygen atom. If you calculate how much mass of air you have, you can assume that these chemical constituents are distributed throughout it uniformly and then calculate the percent of these chemical components in dry air.
You can also use the specific weight, the ratio of the weight to volume in calculating density. The specific weight γ ("gamma") is given by the equation
\gamma = \frac{mg}{V}=\rho gγ=
V
mg
=ρg
that adds an additional variable g as the constant of gravitational acceleration 9.8 m/s2. In this case, the product of mass and gravitational acceleration is the weight of the gas, and dividing this value by the volume V can tell you the gas's specific weight.