1.

At what partial pressure, oxgyenwill have a solubility of "0.05 g L"^(-1) in water at 293 K ? Henry's constant (K_(H)) for O_(2) in water at 293 K is 34.86 kbar. Assume the density of the solution to be same as that of the solvent .

Answer»

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SOLUTION :Calculation of mole fraction `(x_(O_(2)))`
MASS of 1 L of solutio = 1000 g`""(because d ="1 g mL"^(-1))`
`therefore"Mass of solvent (water) "=1000g-0.05 g~=1000g`
`therefore""n_(H_(2)O)=("1000 g")/("18 g MOL"^(-1))="55.5 moles,"n_(O_(2))=("0.05 g")/("32 g mol"^(-1))=1.56 xx10^(-3)" mole"`
`therefore""x_(O_(2))=(n_(O_(2)))/(n_(O_(2))+n_(H_(2)O))~=(n_(O_(2)))/(n_(H_(2)O))=(1.56xx10^(-3))/(55.5)=2.81xx10^(-5)`
Calculation of partial pressure. Applying Henry's law,
`p_(O_(2))=K_(H)xx x_(O_(2))=(34.86xx10^(3)" bar")xx(2.81xx10^(-5))="0.98 bar."`


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