To determine the number of moles of
N2 gas that would dissolve in 1 liter of water at 293 K , when
N2 exerts a partial pressure of 0.987 bar, we can use Henry's Law. Given that the Henry's Law constant
(KH) for
N2 at 293 K is 76.48 K bar, we apply the following:
Henry's Law
P=KHâ‹…X Where:
P is the partial pressure of the gas ( 0.987 bar ),
KH is Henry's Law constant ( 76.48 K bar),
X is the mole fraction of the gas in the solvent.
Calculating Mole Fraction of
N2The mole fraction
XN2 is given by:
XN2=‌=‌=1.29×10−5Determining Moles of Water
The number of moles of water (
nH2O ) in 1 liter ( 1000 grams) is:
nH2O=‌=55.5 Relating Mole Fraction and Moles of
N2The mole fraction can also be expressed as:
XN2=‌≈‌Setting this equal to the previously calculated mole fraction:
1.29×10−5=‌ Solving for
n (the moles of
N2 ):
nN2=1.29×10−5×55.5=7.16×10−4Thus, the number of moles of
N2 gas dissolved in 1 liter of water is
7.16×10−4.