Question

At constant temperature $250mL$ of argon at a $760mmHg$ pressure and $60mL$ of nitrogen at $500mm$ pressure are put together in one litre flask. The final pressure is _________ $mmHg$.

Answer 1

$PV=nRT$

For Argon, $P=760mmHg=1atm$

$V=0.25L$

So, $n=\frac{1\times 0.25}{RT}=\frac{1}{4RT}$

For Nitrogen, $P=500mmHg=\frac{500}{760}atm$

$V=0.06L$

So, $n=\frac{500\times 0.06}{760RT}=\frac{3}{76RT}$

After mixing both the gases,

Total number of moles of both the gases, $n=\frac{1}{4RT}+\frac{3}{76RT}=\frac{88}{304RT}$

$V=1L$

$P=\frac{nRT}{V}=\frac{88}{304RT}\times RT=\frac{88}{304}atm$

$P=\frac{88}{304}\times 760mmHg=220mmHg$