Question

Equal masses of $S{O}_2,C{H}_4$ and $O_2$ are mixed in empty container at $298K$, when the total pressure is $2.1atm$. The partial pressures of $C{H}_4$ in the mixture is :

• A. $0.5atm$
• B. $0.75atm$
• C. $1.2atm$
• D. $0.6atm$

Answer 1

The correct option is C $1.2atm$

Let us take $x$ gm of each of the components.

Molecular Mass of $S{O}_2=64$

$\therefore$ moles of $S{O}_2=\frac{x}{64}$

Molecular Mass of $C{H}_4=16$

$\therefore$ moles of $C{H}_4=\frac{x}{16}$

Molecular Mass of $O_2=32$

$\therefore$ moles of $O_2=\frac{x}{32}$

Total Moles = $\frac{x}{64}+\frac{x}{16}+\frac{x}{32}=\frac{7x}{64}$

Mole fraction of $C{H}_4=\frac{x/16}{7x/64}=\frac{4}{7}$

Hence, partial pressure of $C{H}_4$ = mole fraction $\times$ total pressure = $\frac{4}{7}\times 2.1=1.2$ atm

So, the correct option is $C$