ap chemistry
posted by garm .
A volume of 2.0 L of He at 46 degrees celsius and 1.2 atm of pressure was added to a vessel that contained 4.5 L of N2 at STP. What is the total pressure and partial pressure of each gas at STP after the He is added?

I would use (P1V1/T1) = (P2V2/T2) where P2V2 and T2 are standard conditions. Solve for He pressure at the P2, V2, and T2 conditions. That will give you partial pressure He.
Isn't the partial pressure of N2 just 1 atm or 760 torr?