CO(g) is dissolved in H2O at 30oC and 0.020 atm. Henry's law constant for this system is 6.20×104 atm. Thus, mole fraction of CO(g) is

The mole fraction of a gas in solution is related to partial pressure of the gas above the solution by Henry's law. ρCO=χCOKH∴χCO=ρCOKH=0.020 atm6.20×104 atm=3.22×10-7