a 3 liter flask at 25 C is filled with a mixture of N2 AND O2 to a total pressure of 8 atm, there were 10 grams of N2. How many grams o2 were present?
find the moles of N2.
PV=nRT use this for nitrogen gas, find the partial pressure P for that gas.
Now, the pressure of O2 must be 8atm-P.
Use PV=nRT to find n moles of O2, then convert that to grams.