The air is a mixture of a number of gases. The major components are oxygen and nitrogen with approximate proportion of 20% is to 79% by volume at 298 K. The water is in equilibrium with air at a pressure of 10 atm. At 298 K if the Henry’s law constants for oxygen and nitrogen at 298 K are 3.30 × 107 mm and 6.51 × 107 mm respectively, calculate the composition of these gases in water.


Given-


KH for O2 = 3.30 × 107 mm Hg,


KH for N2 = 6.51 × 107 mm Hg


Percentage of oxygen (O2) = 20 %


Percentage of nitrogen (N2) = 79%


Total pressure = 10 atm


Using Henry’s law,




where, p is the partial pressure of gas in the solution and KH is Henry’s constant.


Now, to determine the mole fraction of oxygen in solution, , we use




To determine the mole fraction of nitrogen in solution, ,




Thus, the mole fraction of oxygen in solution, xoxy = 4.61x10-5


and the mole fraction of nitrogen in solution, xnit is 9.22x10-5


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