A closed container with a mixture of hydrogen, helium, and argon has a total pressure of 3.00 atm. The partial pressure of hydrogen is 0.550 atm and the partial pressure of argon is 615 mm Hg. What is the partial pressure of helium?
Ptotal = PHe + PH2 + PAr
Substitute and solve for the only unknown.
CAUTION: You MUST have the pressures in the same unit. They are in different units in the problem.
To find the partial pressure of helium in the mixture, we first need to convert the partial pressures of hydrogen and argon to the same unit of pressure.
Given:
Total pressure = 3.00 atm
Partial pressure of hydrogen = 0.550 atm
Partial pressure of argon = 615 mm Hg
To convert mm Hg to atm, we use the conversion factor: 1 atm = 760 mm Hg.
Converting the partial pressure of argon:
615 mm Hg * (1 atm / 760 mm Hg) = 0.809 atm
Now that we have the partial pressures of hydrogen and argon in the same unit, we can calculate the partial pressure of helium by subtracting the sum of the partial pressures of hydrogen and argon from the total pressure.
Partial pressure of helium = Total pressure - (Partial pressure of hydrogen + Partial pressure of argon)
Partial pressure of helium = 3.00 atm - (0.550 atm + 0.809 atm)
Partial pressure of helium = 3.00 atm - 1.359 atm
Partial pressure of helium = 1.641 atm
Therefore, the partial pressure of helium in the mixture is 1.641 atm.