Exercise 5 | Properties of Gases

Calculate the density (in g.L-1) of the methane CH4 (g) at 10.0°C and 1.00 atm.

ρ = m / V


Ideal-gas equation:

PV = nRT

⇒ PV = mRTM

mV = PMRT

⇒ ρ = PMRT


P = pressure in Pa ⇒ 1.00 atm = 1.013 x 105 Pa

M = molar mass ⇒ M = MC + 4 x MH = 16.4 g.mol-1

R = ideal gas constant = 8.314 m3.Pa.K-1.mol-1

T = temperature in K ⇒ 10.0°C = 288 K


ρ = 1.013 × 105 × 16.48.314 × 288 = 6.94 x 102 g.m-3 = 6.94 x 10-1 g.L-1