Question

A gaseous mixture contains 56 $g$ of $N_2$, 44 $g$ of $C{O}_2$ and 16 $g$ of $C{H}_4$. The total pressure of the mixture is 720 $mm$ of $Hg$. The partial pressure of $C{H}_4$ in $mm$ of $Hg$ is:

• A. $180$
• B. $360$
• C. $540$
• D. $720$

Answer 1

The correct option is A $180$

no. of moles of nitrogen gas $=\frac{56}{28}=2$
no . of moles of carbon-dioxide gas $=\frac{44}{44}=1$
no. of moles of methane $=\frac{16}{16}=1$
Total no. of moles in the mixture = $4$
Thus, mole fraction of methane $=X_{C{H}_4}=1:4$
$P_{C{H}_4}=P.X_{C{H}_4}$
$X_{C{H}_4}=\frac{1}{4}$
$P_{C{H}_4}=180$ $mm$