Question

250 $mL$ of nitrogen gas maintained at 720 $mm$ pressure and 380 $mL$ of oxygen gas maintained at 650 $mm$ pressure are put together in 1 $L$ flask. If temperature is kept constant, what will be the final pressure of $O_2$ in the mixture?

Answer 1

$P_{N_2}[P_2=\frac{P_1{V}_1}{V_2}]=\frac{720\times 250}{1000}\left(1Lofflask\right)=180mm$
$P_{O_2}=\frac{380\times 650}{1000}=247mm$
According to Dalton's law,
$P=P_1+P_2=180+247=427mm$