Oxygen is bubbled through water before it is given to a patient in a hospital.
What volume of pure oxygen gas at 21.0°C and 750.0 torr pressure would a patient receive if the patient breathed 0.250 L of O₂ bubbled through water at this temperature and pressure? (P_H₂_O = 19.0 torr at 21°C)

Question

Quizplus · Accepted Answer

The volume of pure oxygen gas can be calculated using Dalton's Law of Partial Pressures. The partial pressure of oxygen in the mixture is the total pressure minus the vapor pressure of water at 21°C (750.0 torr - 19.0 torr = 731.0 torr). Using the ideal gas law and assuming the volume of gases before and after bubbling is the same, the volume of pure oxygen can be calculated. Since the pressure of pure oxygen is slightly less than the total pressure due to the presence of water vapor, the volume of pure oxygen that the patient receives is slightly less than the total volume of the gas mixture bubbled through water. Therefore, the correct answer is 0.244 L, which accounts for the reduction in volume due to the water vapor pressure.

Oxygen Is Bubbled Through Water Before It Is Given to a Patient