1. Tardigrade
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  3. Chemistry
  4. The vapour pressure of n-hexane at 350 K is 840 torr and that of cyclohexane is 600 torr. Mole fraction of hexane in the mixture that boils at 350 K and 1 atm pressure assuming ideal behaviour is

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Q. The vapour pressure of $n$-hexane at $350\, K$ is $840$ torr and that of cyclohexane is $600$ torr. Mole fraction of hexane in the mixture that boils at $350\, K$ and $1 $ atm pressure assuming ideal behaviour is

Solutions

Solution:

Mixture boils at $1$ atm and $350 \,K$
Thus, total vapour pressure is $1$ atm = $760$ torr
(h) used for hexane and (ch) for cyclohexane
$P_{\text{total}}=P_{h}^{o} \, \chi_{h}^{o}+P_{ch}^{o} \, \chi_{ch}$
$\Rightarrow P_{\text{total}} =P_{h}^{o}\,\chi_{h}+P_{ch}^{o}\left(1-\chi_{h}\right)$
$760=840_{\chi_h}+600\left(1-\chi_{h}\right)$
$\therefore \chi_{h}=0.67$