When 0.578 L of Ar at 1.20 atm and 227°C is mixed with 0.299 L of O2 at 501 torr and 127°C in a 400. mL flask at 27°C, what is the pressure in the flask?

Answer 1

Use PV = nRT and solve for n for Ar.
Use PV = nRT and solve for n for O2.
Add n for Ar + n for O2 for total n.
Use PV = nRT with new conditions and total n and solve for p.