CET Karnataka Medical CET - Karnataka Medical Solved Paper-2012

  • question_answer
    A given sample of milk turns sour at room temperature \[({{27}^{o}}C)\] in 5 hours. In a refrigerator at \[-{{3}^{o}}C\], it can be stored 10 times longer. The energy of activation for the souring of milk is

    A)  \[2.303\times 10\text{ }R\text{ }kJ.mo{{l}^{-1}}\]

    B)  \[2.303\times 5\text{ }R\text{ }kJ.mo{{l}^{-1}}\]

    C)  \[2.303\times 3\text{ }R\text{ }kJ.mo{{l}^{-1}}\]

    D)  \[2.303\times 2.7\text{ }R\text{ }kJ.mo{{l}^{-1}}\]

    Correct Answer: D

    Solution :

    : Rate of souring of milk at \[{{27}^{o}}C\]is 10 times faster than at \[-{{3}^{o}}C\]. hence, \[\frac{{{k}_{300}}}{{{k}_{270}}}=10,\,\,{{T}_{1}}=270K,\,\,{{T}_{2}}=300K\] \[{{E}_{a}}=2.303R\left( \frac{{{T}_{1}}{{T}_{2}}}{{{T}_{2}}-{{T}_{1}}} \right)\log \frac{{{k}_{300}}}{{{k}_{270}}}\] \[{{E}_{a}}=2.303R\left( \frac{270\times 300}{300-270} \right)\log 10\] \[{{E}_{a}}=2.303R(2.7\times {{10}^{3}})Jmo{{l}^{-1}}\] \[{{E}_{a}}=2.303\times 2.7R\,kJ\,mo{{l}^{-1}}\]


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