Question:
The volume occupied by $4.75 \mathrm{~g}$ of acetylene gas at $50^{\circ} \mathrm{C}$ and $740 \mathrm{mmHg}$ pressure is (Rounded off to the nearest integer) $\left[\right.$ Given $\mathrm{R}=0.0826 \mathrm{~L}$ atm $\left.\mathrm{K}^{-1} \mathrm{~mol}^{-1}\right]$
Solution:
Given Mass $=4.75 \mathrm{~g} \Rightarrow \mathrm{C}_{2} \mathrm{H}_{2}(\mathrm{~g})$
$\Rightarrow$ Moles $=\frac{4.75}{26} \mathrm{~mol}$
$\mathrm{Temp}=50+273=323 \mathrm{~K}$
$\mathrm{P}=\frac{740}{760} \mathrm{~atm}$
$\mathrm{R}=0.0826 \frac{\ell \mathrm{atm}}{\mathrm{molK}}$
$\Rightarrow \mathrm{V}=\frac{\mathrm{nRT}}{\mathrm{P}}=\frac{4.75}{26} \times \frac{0.0826 \times 323}{\left(\frac{740}{760}\right)}$
$\Rightarrow \quad V=\frac{96314.078}{19240}=5.0059 \ell \simeq 5 \ell$