Question

The partial pressure of oxygen gas in our atmosphere is 0.21 atm. this is the partial pressure at which human lungs have evolved to be able to breathe this gas. a scuba diver, will thus still have to breath oxygen at this pressure even when diving way down in the water. if a mixture of helium and oxygen (heliox) in his tank is at a pressure of 7.00 atm, what must the partial pressure be of helium to keep the partial pressure of oxygen at 0.21 atm?

a) 7.21 atm
b) 6.79 atm
c) 7.00 atm
d) 0.21 atm

Answer 1

To keep the partial pressure of oxygen at 0.21 atm in a heliox mixture at a pressure of 7.00 atm, the partial pressure of helium should be approximately 6.79 atm.

Step-by-step explanation:

To keep the partial pressure of oxygen at 0.21 atm in a heliox mixture at a pressure of 7.00 atm, we can use Dalton's law of partial pressures. Dalton's law states that the total pressure of a gas mixture is equal to the sum of the partial pressures of each gas component. In this case, the partial pressure of helium plus the partial pressure of oxygen should equal the total pressure of the heliox mixture.

Let's assume the partial pressure of helium is x. Then, the partial pressure of oxygen is 7.00 atm - x. We need to set up the equation:

x + (7.00 atm - x) = 0.21 atm

Simplifying the equation:

7.00 atm - x = 0.21 atm

x = 7.00 atm - 0.21 atm

x ≈ 6.79 atm

Therefore, the partial pressure of helium must be approximately 6.79 atm to keep the partial pressure of oxygen at 0.21 atm in the heliox mixture.