The solubility of oxygen in lakes high in the Rocky Mountains is affected by the altitude. If the solubility of O₂ from the air is 2.67 * 10^-4 M at sea level and 25°C, what is the solubility of O₂ at an elevation of 12,000 ft where the atmospheric pressure is 0.657 atm? Assume the temperature is 25°C, and that the mole fraction of O₂ in air is 0.209 at both 12,000 ft and at sea level. A)1.75 * 10^-4 M B)2.67 * 10^-4 M C)3.66 * 10^-5 M D)4.06 * 10^-4 M E)None of the above.

Question

Quizplus · Accepted Answer

The solubility of oxygen in water can be calculated using Henry's Law:

C = kP

where C is the concentration of dissolved oxygen, k is the Henry's Law constant, and P is the partial pressure of oxygen in the air.

At sea level: 
C = kP = (2.67 x 10^-4 M/atm) x (1 atm x 0.209) = 5.59 x 10^-5 M

At 12,000 ft: 
C = kP = (2.67 x 10^-4 M/atm) x (0.657 atm x 0.209) = 1.75 x 10^-5 M

Therefore, the solubility of oxygen at 12,000 ft is 1.75 x 10^-5 M. The best choice is A.

The Solubility of Oxygen in Lakes High in the Rocky