Question

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

Answer 1

Total pressure of air in equilibrium with water = 10 atm 

As air contains 20% oxygen and 79% nitrogen by volumes partial pressure of oxygen : 

(P) = \(\frac{20}{100}\) x 10 atm = 2atm 

= 2 x 760 mm = 1520 mm 

partial pressure of nitrogen P_N2

= \(\frac{79}{100}\) × 10 atm = 7.9 atm = 7.9 x 760 mm 

= 6004 mm

KH(O₂) = 3.30 x 10⁷ mm, K_H (N₂) = 6.51 × 10⁷ mm 

Applying Henry’s law