Air is approximately 79% nitrogen and 21% oxygen by volume. How many moles of oxygen are present in 22.0 L of 24 C and a pressure of 53 kPa?

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Answer 1 · 2017-05-16T00:09:08

According to Dalton's law of partial pressure, the total pressure of the system is

#P_t = n_t((RT)/V)#

Convert given units into appropriate units for the gas equations:

#24 ^oC = 297 K#

and

#53 kPa = 0.52 atm#

The total moles in the system:

#n_t = ((0.52 atm)(22.0 L))/((0.08206 (L-atm)/(mol-K))(297 K)) = 0.47 mol#

So, using mole fractions of each molecule,

#mol_(N_2) = (0.79)(0.47 mol) = 0.37 mol_(N_2)#

and

#mol_(O_2) = (0.21)(0.47 mol) = 0.099 mol_(O_2)#