Calculate the mass of oxygen (in mg) dissolved in a 5.00 L bucket of water exposed to a pressure of 1.13 bar of air. Assume the mole fraction of oxygen in air to be 0.21 and the Henry's law constant for oxygen in water at this temperature to be 1.3 × 10^-3 mol L^-1 bar^-1. A) 49.4 mg B) 23.5 mg C) 9.87 mg D) 27.3 mg E) 13.7 mg

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Quizplus · Accepted Answer

To find the mass of oxygen dissolved, use Henry's law: C = kP. Here, C is the concentration of dissolved oxygen, k is the Henry's law constant, and P is the partial pressure of oxygen. P = 0.21 × 1.13 bar = 0.2373 bar. C = 1.3 × 10^-3 mol/L/bar × 0.2373 bar = 3.0859 × 10^-4 mol/L. For 5 L, moles of O2 = 5 × 3.0859 × 10^-4 = 1.54295 × 10^-3 mol. Mass = moles × molar mass of O2 (32 g/mol) = 1.54295 × 10^-3 × 32 = 0.0493744 g = 49.4 mg.

Calculate the Mass of Oxygen (In Mg) Dissolved in a 5.00