posted by Mary .
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.