The number of moles per mm³=2.032 x 10⁻⁹
In general, the gas equation can be written
[tex]\large {\boxed {\bold {PV = nRT}}}[/tex]
where
P = pressure, atm , N/m²
V = volume, liter
n = number of moles
R = gas constant = 0.082 l.atm / mol K (P= atm, v= liter),or 8.314 J/mol K (P=Pa or N/m2, v= m³)
T = temperature, Kelvin
P=1.3 kPa=1.3.10³ N/m²
T = 77 K
R = 8.31 J/mol.K
[tex]\tt PV=nRT\\\\\dfrac{n}{V}=\dfrac{P}{RT}\\\\\dfrac{mol}{m^3}=\dfrac{1.3\times 10^3}{8.31\times 77}\\\\\dfrac{mol}{m^3}=2.032\\\\2.032\dfrac{mol}{m^3}\times \dfrac{m^3}{10^9cm^3}=2.032\times 10^{-9}\dfrac{mol}{cm^3}[/tex]
