The Henry's law constant (kH) for O2 in water at 20°C is 1.28 * 10-3 mol / (L·atm). (a) How many grams of O2 will dissolve in 4.00 L of H2O that is in contact with pure O2 at 1.00 atm? g O2 (b) How many grams of O2 will dissolve in 4.00 L of H2O that is in contact with air where the partial pressure of O2 is 0.209 atm?

Solubility of O₂ (g) in 4L water = 3.42 x 10⁻² grams O₂ (g)

Explanation:

Graham's Law = > Solubility (S) ∝ Applied Pressure (P) = > S = k·P

Given P = 0.209Atm & k = 1.28 x 10⁻³mol/L·Atm

=> S = k·P = (1.28 x 10⁻³ mole/L·Atm) 0.209Atm = 2.68 x 10⁻³ mol O₂/L water.

∴Solubility of O₂ (g) in 4L water at 0.209Atm = (2.68 x 10⁻³mole O₂ (g) / L) (4L) (32 g O₂ (g) / mol O₂ (g)) = 3.45 x 10⁻² grams O₂ (g) in 4L water.