ESS55
Prof. Jin-Yi Yu
Gas Constant
qThe ideal gas law can be applied to the combination of atmospheric gases or to individual gases.
qThe value of gas constant for the particular gas under consideration depends on its molecular weight:
q                     Rgas = R* / Mgas 
q      where R* = universal gas constant = 8314.3 J deg-1 kg-1 
qThe gas constant for dry atmospheric air is:
q      Rair = R* / Mair = 8314.3/28.97 = 287 J deg-1 kg-1
q      (Mair @ 0.80*MN2 + 0.20*MO2 = 0.80*28 + 0.2*32 = 28.8)
qThe gas constant for water vapor is:
q     Rvapor = R* / Mvapor = 8314.3/18.016
q               = 461 J deg-1 kg-1