States of Matter - Result Question 76
76. The composition of the equilibrium mixture $\left(Cl _2 \rightleftharpoons 2 Cl\right)$ which is attained at $1200^{\circ} C$, is determined by measuring the rate of effusion through a pin-hole. It is observed that at $1.80 mm Hg$ pressure, the mixture effuses 1.16 times as fast as krypton effuses under the same conditions. Calculate the dfraction of chlorine molecules dissociated into atoms (atomic weight of $Kr=84)$
$(1995,4 M)$
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Answer:
Correct Answer: 76. (0.14)
Solution:
If ’ $\alpha$ ’ is the degree of dissociation, then at equilibrium
$ \quad \quad \quad \quad \quad Cl _2 \quad \rightleftharpoons \quad 2 Cl $
$\text { Moles } \hspace {5mm} 1-\alpha \quad \quad \quad 2 \alpha$ $ \quad \text { Total }=1+\alpha $
From diffusion information
$ \dfrac{r _{(\text {mix })}}{r _{(Kr)}} =1.16=\sqrt{\dfrac{84}{M(mix)}}$
$\Rightarrow M _{(\text {mix })} =62.4 $
$\Rightarrow M _{(\text {mix })} =\dfrac{71}{1+\alpha}=62.4 $
$\Rightarrow \alpha =0.14$
BETA
