# 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 = $\frac{\mathrm{mRT}}{\mathrm{M}}$

$\frac{\mathrm{m}}{\mathrm{V}}$ = $\frac{\mathrm{PM}}{\mathrm{RT}}$

⇒ ρ = $\frac{\mathrm{PM}}{\mathrm{RT}}$

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 =  = 6.94 x 102 g.m-3 = 6.94 x 10-1 g.L-1