# What is the formula for the density of gases?

###### Wiki User

###### 2011-09-14 10:02:01

"mass_/_volume" id="mass_/_volume">mass / volume

If you just want to measure it, all you need is the mass of the gas

inside the container and the volume of the container

Density = mass / volume

In general, the density of a gas depends on several things: the

molecular weight of the gas, the temperature, and the pressure. For

an ideal gas, the following equation holds:

P*V = n*R*T

where P is the pressure (in atmospheres, ATM), V is the volume

(in liters, L), n is the number of moles, R is the gas constant (R

= 0.0820574587 L ATM K-1 mol-1), and T is the temperature (in

Kelvin, K).

The density of a gas is the number of grams per volume (usually

in g/mL or kg/L). Taking the molar mass (MM) of a substance and

multiplying it times the number of moles gives the number of grams.

Therefore for an ideal gas, using that fact and rearranging the

equation above, we have:

Density = (n*MM)/V = (P*MM)/(R*T)

Make sure your units agree in any and all calculations!