VMMC VMMC Medical Solved Paper-2009

  • question_answer
    The rate of a gaseous reaction triples when temperature is increased by \[\text{1}{{\text{0}}^{\text{o}}}\text{C}\] from \[\text{2}{{\text{5}}^{\text{o}}}\text{C}\text{.}\]The energy of activation of the reaction(in \[\text{kJ}\,\text{mo}{{\text{l}}^{-1}}\]) will be

    A) 40                                          

    B) 70          

    C) 83.8                       

    D)        200

    Correct Answer: C

    Solution :

    Given, \[{{T}_{1}}=25{{\,}^{o}}C=25+273=298\,K\] \[{{T}_{2}}=(25+10{{\,}^{o}}C)=35{{\,}^{o}}C=308\,K\] \[Rat\propto k\] \[\Rightarrow \]                \[\frac{{{(Rate)}_{{{25}^{o}}}}}{{{(Rate)}_{{{35}^{o}}}}}=\frac{{{k}_{{{25}^{o}}}}}{{{k}_{{{35}^{o}}}}}\]                 \[\frac{{{k}_{{{25}^{o}}}}}{{{k}_{{{35}^{o}}}}}=\frac{1}{3}\] From Arrhenius equation, \[\log \frac{{{k}_{{{35}^{o}}}}}{{{k}_{{{25}^{o}}}}}=\frac{{{E}_{a}}}{2.303R}\left[ \frac{1}{{{T}_{1}}}-\frac{1}{{{T}_{2}}} \right]\] \[\log 3=\frac{{{E}_{a}}}{2.30\times 8.314\times {{10}^{-3}}}\left[ \frac{1}{298}-\frac{1}{308} \right]\] \[0.477=\frac{{{E}_{a}}}{2.30\times 8.314\times {{10}^{-3}}}\left[ \frac{10}{298\times 308} \right]\]                 \[\therefore \]  \[{{E}_{a}}=83.8\,kJ\,mo{{l}^{-1}}\]


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