Some Basic Concepts of Chemistry 1 Question 39
59. The vapour density (hydrogen $=1$ ) of a mixture consisting of $\mathrm{NO}{2}$ and $\mathrm{N}{2} \mathrm{O}{4}$ is 38.3 at $26.7^{\circ} \mathrm{C}$. Calculate the number of moles of $\mathrm{NO}{2}$ in $100 \mathrm{~g}$ of the mixture.
$(1979,5 \mathrm{M})$
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Solution:
- From the vapour density information
Molar mass $=$ Vapour density $\times 2\left(\because\right.$ Molar mass of $\left.\mathrm{H}_{2}=2\right)$
$$ =38.3 \times 2=76.6 $$
Now, let us consider 1.0 mole of mixture and it contains $x$ mole of $\mathrm{NO}_{2}$.
$\Rightarrow \quad 46 x+92(1-x)=76.6 \Rightarrow x=0.3348$
Also, in $100 \mathrm{~g}$ mixture, number of moles $=\frac{100}{76.6}$
$\Rightarrow$ Moles of $\mathrm{NO}_{2}$ in mixture $=\frac{100}{76.6} \times 0.3348=0.437$
