A balloon contains 0.1 moles of oxygen and 0.4 moles of nitrogen. If the balloon is at standard temperature and pressure, what is the partial pressure of the nitrogen?
Partial pressure is found by Dalton's Law
Px = PTotal ( nx / nTotal )
Px = partial pressure of gas x
PTotal = total pressure of all gases
nx = number of moles of gas x
nTotal = number of moles of all gases
Standard pressure is 1 atm
nTotal = noxygen + nnitrogen
nTotal = 0.1 mol + 0.4 mol
nTotal = 0.5 mol
Solve for Pnitrogen
Pnitrogen = PTotal ( nnitrogen / nTotal )
Pnitrogen = 1 atm ( 0.4 mol / 0.5 mol )
Pnitrogen = 0.8 atm
The partial pressure of the nitrogen is 0.8 atm.