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Vapor pressure in equilibrium

  1. Mar 8, 2005 #1
    I have difficulties with a problem that my teacher gave in assignement. Teh teacher said it was a bit higher than our level but I think it far above what I am able to do! so here it is :

    The vapor pressure in equilibrium with pentane-hexane solution at 25°C has a mole fraction of pentane equal to 0.15 at that temperature. What is the mole fraction in the solution?

    Up to now I found that the vapor pressure of pentane is 511 torr and the one of hexane is 150 torr. I think that I should use Raoult's law but my attempts were not concluant... I hope someone will be able to answer my question.
  2. jcsd
  3. Mar 12, 2005 #2


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    [tex]P^o (P) = 511~,~~P^o (H) = 150 [/tex]

    [tex]P(P) = \chi (P.solution) * P^o (P)= 0.15P(tot) [/tex]

    [tex]=>~0.15P(tot) = \chi (P)* 511 [/tex]

    [tex]And~0.85P(tot) = (1 - \chi(P))*150 [/tex]
    Last edited: Mar 12, 2005
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