Some Basic Concepts of Chemistry - Result Question 60
####59. The vapour density (hydrogen $=1$ ) of a mixture consisting of $NO _2$ and $N _2 O _4$ is 38.3 at $26.7^{\circ} C$. Calculate the number of moles of $NO _2$ in $100 g$ of the mixture.
$(1979,5 M)$
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Solution:
- From the vapour density information
Molar mass $=$ Vapour density $\times 2\left(\because\right.$ Molar mass of $\left.H _2=2\right)$
$$ =38.3 \times 2=76.6 $$
Now, let us consider 1.0 mole of mixture and it contains $x$ mole of $NO _2$.
$\Rightarrow \quad 46 x+92(1-x)=76.6 \Rightarrow x=0.3348$
Also, in $100 g$ mixture, number of moles $=\frac{100}{76.6}$
$\Rightarrow$ Moles of $NO _2$ in mixture $=\frac{100}{76.6} \times 0.3348=0.437$
