Dry air near sea level has the following composition by volume: N2, 78.08 percent; O2, 20.94 percent; Ar, 0.93 percent; CO2, 0.05 percent. The atmospheric pressure is 1.00 atm. Calculate the concentration of each gas in moles per liter at 0°C?

1 Answer
SCooke
Sep 19, 2017

#N_2 = 0.0348 (mol)/L#
#O_2 = 0.00934 (mol)/L#
#Ar = 0.00041 (mol)/L#
#CO_2 = 0.000022 (mol)/L#

Explanation:

The percentages do not change, so you really only need to calculate the total moles at the temperature and volume to find the ratios.

#PV = nRT# is the defining equation. We have 1.00atm pressure, 0'C (273'K) and 1 liter volume. The gas constant R for these dimensions is #0.0821 (L xx atm)/('K xx mol)#

#n = (PV)/(RT)# ; #n = (1 xx 1)/(0.0821 xx 273) = 0.0446# Total Moles/Liter.

#N_2 = 0.7808 xx 0.0446 = 0.0348 (mol)/L#
#O_2 = 0.2094 xx 0.0446 = 0.00934 (mol)/L#
#Ar = 0.0093 xx 0.0446 = 0.00041 (mol)/L#
#CO_2 = 0.0005 xx 0.0446 = 0.000022 (mol)/L#

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