Question

A mixture of $CO$ and $C{O}_2$ is found to have a density of 1.5 gm/L at ${30}^{o}C$ and 740 mm pressure. The percentage composition of $C{O}_2$ in the mixture is:

• A. 64.5%
• B. 61.5%
• C. 74.5%
• D. 71.5%

Answer 1

The correct option is A 64.5%

$PV=nRT$
$⟹PV=\frac{mass}{moleularweight}RT$
$⟹\frac{mass}{V}=\frac{P\times moleularweight}{RT}$
$⟹d=\frac{P\times M_{avg}}{RT}$, where $M_{avg}$ is the molecular weight of the mixture.
$⟹1.5=\frac{\frac{740}{760}\times M_{avg}}{0.0821\times 303}$
Let $x$ be the percentage composition of $C{O}_2$ in the mixture.
$⟹M_{avg}=38.32=\frac{x\times 44+(100-x)\times 28}{100}$
$⟹x=64.5\%$.