What is the partial pressure?

Question

If a 1.6 −L reaction vessel initially contains 760 torrtorrof N2O5N2O5 at 25 ∘C, what partial pressure of O2O2 will be present in the vessel after 230 minutes?

Answer 1

For a first order reaction fraction remaining (FR) = 0.5ⁿ where n = number of half lives elapsed

Converting half life to minutes, we have...

2.81 hours x 60 minutes/hr = 168.6 minutes = half life

half lives elapsed = 230 minutes x 1 half life / 168.6 minutes = 1.36 half lives = n

FR = 0.5^1.36 = 0.390

Pressure remaining = 0.390 x 760 torr = 296 torr