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Hyperbaric oxygenation therapy involves placing a patient in a chamber with oxygen-rich air at greater than atmospheric pressure. Normal air has approximately 78% N₂, 21% O₂, and trace amounts of other gases. The pressure within the hyperbaric chamber is typically measured in terms of ATA, or atmospheres absolute (1 ATA is the average atmospheric pressure at sea level, or 1 atm) . A hyperbaric chamber set at 2.5 ATA would be the average atmospheric pressure at sea level (1 ATA) plus the additional pressure applied to the chamber (1.5 ATA) .There are two main types of hyperbaric chambers: monoplace chambers and multiplace chambers. Monoplace chambers accommodate a single person. The air in these chambers is 100% oxygen and can be raised to a maximum pressure of 3 ATA. Monoplace chambers are used as therapy for conditions where oxygen supply has been depleted, such as carbon monoxide poisoning. They are also used when a higher concentration of oxygen in plasma is needed, such as in wound healing.Multiplace chambers are large enough to house at least four people. The air in these chambers is typically a mixture of oxygen and nitrogen, but the patient breathes pure oxygen through a mask. Some multiplace chambers can endure maximum pressures of 6 ATA and are typically used to eliminate intravascular air bubbles that can occur from decompression sickness or embolisms. The high pressure from the multiplace chamber results in a decrease in volume of any air pockets within the body, including the sinuses, inner ear, and unwanted air bubbles in the arteries or veins.Patients report that their ears "pop" during the pressurization process, similar to being on an airplane in flight. In addition, they report that although there is an initial sense of temperature increasing, the chamber's temperature stays relatively stable during both the pressurization and the depressurization processes.
-What is the partial pressure of O₂ in a 3-ATA multiplace chamber filled with 80% O₂ and 20% N₂?

Question

Quizplus · Accepted Answer

11ecba2d_1206_25a7_a3bf_0b6a99c0796c_MD0008_00 For ideal gases, the identity of a gas is unimportant for determining the pressure of the gas. In a container with a mixture of gases, the total pressure is equal to the sum of the partial pressures of each of the gases within the container. This is known as Dalton's law of partial pressures. Because the pressure of an ideal gas is based on the number of moles of gas particles, the partial pressure of a particular gas can be determined using a mole fraction. The mole fraction χ is the ratio of the number of moles of an individual gas to the total number of moles. 11ecba2d_1206_25a8_a3bf_dfadad5fbddd_MD0008_00 In this question, the mole fraction is given as a percentage. If the chamber contains 80% oxygen, then the mole fraction is 80/100, or 0.80. Substituting the mole fraction and pressure values into the equation for partial pressure gives: 11ecba2d_1206_4cb9_a3bf_5390f42dd759_MD0008_00 Therefore, the partial pressure of O₂ in a 3-ATA multiplace chamber filled with 80% O₂ is 2.4 ATA. (Choice A) A pressure of 0.2 ATA is obtained if only the mole fraction of N₂ is used rather than multiplying the mole fraction of O₂ by the total pressure. (Choice B) A pressure of 0.6 ATA is the partial pressure of N₂. This is obtained by using the mole fraction of N₂ (0.20) in the calculation rather than the mole fraction of O₂ (0.80). (Choice D) A pressure of 3.0 ATA is the total pressure of the chamber rather than the partial pressure of O₂ in a chamber with a mixture of 80% O₂ and 20% N₂. Educational objective: Dalton's law of partial pressures states that the total pressure of a mixture of gases is equal to the sum of the partial pressure of each of the individual gases. The partial pressure of an individual gas can be found using the mole fraction of the gas multiplied by the total pressure.