A 1L flask is filled with 1.25 g of argon at 25 degrees celcium. A sample of ethane vapor is added to the same flask until the total pressure is 1.45 atm.

What is the partial pressure of argon in the flask?

1 answer

mols Ar = 1.25/39.95 = 0.0313
Use PV = nRT to calculate pressure Ar.
Remember that the partial pressure of a gas doesn't depend upon what other gas is present. In effect, we ignore the ethane vapor although the partial pressure of the ethane COULD be calculated, also.