Question

If a 2litre flask of $N_2$ at ${20}^0$ and 70 cm p is connected with a 3litre another flask of $O_2$ at the same temperature and 100cm P. What will be the final pressure after the gas has thoroughly mixed at same temperature as before? Also report mole % of nitrogen gas in the mixture (as nearest integer)

Answer 1

For $N_2$: V=2litre ,P=70cm,T=273K

$n_{N_2}$=$\frac{PV}{RT}$=$\frac{70\ast 2}{76\ast 0.821\ast 293}$=$7.658\ast {10}^{-2}$

For $O_2:V=3litre,P=1000cm,T=273K$

$n_{O_2}=\frac{PV}{RT}=\frac{100\ast 3}{76\ast 0.821\ast 293}=1.641\ast {10}^{-}2$

After mixing V=5 litre, T=293K

Total mole $=(7.658+16.41)\ast {10}^{-2}$

PV=nRT

$P\ast 5=(7.658+16.41)\ast {10}^{-}2\ast 0.821\ast 293$

P=1.158atm

Also mole % of $N_2=7.658\ast {10}^{-}2\left(\right(7.658+16.41)\ast {10}^{-}2)\ast 100=31.8$%

So, nearest integer is 32.