JEE Main & Advanced Chemistry Solutions / विलयन Sample Paper Topic Test - Solutions

  • question_answer
    A mixture of A and B, which are two miscible liquids, is distilled under equilibrium conditions at atmospheric pressure. The mole fraction of A in solution is 0.3 and in vapour phase is 0.6. If the solution behaves ideally the ratio of \[P\,_{A}^{o}\] to \[P\,_{B}^{o}\] is

    A) 4.0

    B) 2.5                

    C) 3.5

    D) 1.5

    Correct Answer: C

    Solution :

    [c] In solution \[{{X}_{A}}=0.3\]\[\therefore \]\[{{X}_{B}}=0.7\]
    In vapours \[{{Y}_{A}}=0.6\,\,\therefore \,\,{{Y}_{B}}=0.4\]
    Using Dalton's law
    \[{{Y}_{A}}=\frac{{{p}_{A}}}{{{p}_{T}}}\]
    i.e.,      \[{{Y}_{A}}=\frac{p_{A}^{o}\times {{X}_{A}}}{P_{A}^{o}{{X}_{A}}+p_{B}^{o}{{X}_{B}}}\]
    \[\therefore \]    \[{{Y}_{B}}=\frac{p_{B}^{o}{{X}_{B}}}{p_{A}^{o}{{X}_{A}}+p_{B}^{o}{{X}_{B}}}\]
    \[\therefore \]            \[\frac{{{Y}_{A}}}{{{Y}_{B}}}=\frac{p_{B}^{o}{{X}_{B}}}{p_{B}^{o}{{X}_{B}}}\]
    \[\therefore \]    \[\frac{p_{{}}^{o}A}{p_{{}}^{o}B}=\frac{{{Y}_{A}}}{{{Y}_{B}}}\times \frac{{{X}_{B}}}{{{X}_{A}}}=\frac{0.6}{0.4}\times \frac{0.7}{0.3}=3.5\]


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