pV = n R T
- p pressure in Pa
- V volume in m3
- n number of moles
- R gas constant R = 8.3145 Jmol-1K-1
- T Kelvin temperature in K
Example
In a tank of 200 ℓ is helium. The pressure in the tank is 30 bar and the temperature is 20 oC.
Calculate the mass of helium.
p V = n R T
(30 x 105)( 200 x 10-3) = n (8.31) (293)
n = ((30 x105)( 200 x 10-3)) / (8.31 x 293) = 246 mol
mass per mol of helium is 4.0 g mol-1
mass of helium : 246 x 4 = 985.7 g = 9.9 x 102 g