Question

How much oxygen is dissolved in 100 mL water at
298 K if partial pressure of oxygen is 0.5 atm and
Ky = 1.4 x 10 mol/L/atm?
(a) 22.4 mg
(b) 22,4 g
(c) 2.24 g
(d) 2.24 mg
​

Answer 1

according to Henry's law,

$S=K_HX_p$

where S is concentration of O2 is dissolved , $K_H$ is Henry's constant and $X_p$ partial pressure of O2

here, $K_H$ = 1.4 × 10^-3 mol/L/atm and $X_p$ = 0.5atm

so, S = 1.4 × 10^-3 × 0.5 = 0.7 × 10^-3 M

now, molarity = number of mole of solute /volume of solution

or, 0.7 × 10^-3 = mass of O2/molecular weight of O2 × volume of solution in L

or, 0.7 × 10^-3 = mass of O2/(32g/mol × 100/1000 L)

or 0.7 × 10^-3 × 3.2 = mass of O2

or, mass of O2 = 2.24 × 10^-3 g = 2.24mg

hence, option (d) is correct choice.

Answer 2

Answer:

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