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JCECE Medical JCECE Medical Solved Paper-2005

  • question_answer
    The enthalpy of vaporization of substance is \[\text{840}\,\text{J}-\text{mo}{{\text{l}}^{-1}}\]and its boiling point is\[-\text{173}{{\,}^{\text{o}}}\text{C}\text{.}\] Its entropy of vaporization is:

    A) \[42\,J\,mo{{l}^{-1}}{{K}^{-1}}\]

    B)  \[21\,J\,mo{{l}^{-1}}{{K}^{-1}}\]

    C)  \[84\,J\,mo{{l}^{-1}}{{K}^{-1}}\]

    D)  \[8.4\,J\,mo{{l}^{-1}}{{K}^{-1}}\]

    Correct Answer: D

    Solution :

     Key Idea:\[\Delta S=\frac{\Delta H}{T}\] \[where\,\Delta S\,=entropy\,of\,vaporisation.\] \[\Delta H=enthalpy\,of\,vaporisation\,=840\,J/mol\] \[T=-173{{\,}^{o}}C=-173+273=100\,K\] \[\therefore \] \[\Delta S=\frac{840}{100}=8.4\,J\,mo{{l}^{-1}}{{K}^{-1}}\]


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