KVPY Sample Paper KVPY Stream-SX Model Paper-19

  • question_answer
    Consider the following reactions at 300 K.
    \[A\to B\](uncatalysed reaction)
    \[A\xrightarrow{\text{catalyst}}B\](catalyst reaction)
    The activation energy is lowered by \[8.314\,\,KJ\,\,mo{{l}^{-1}}\] for the catalysed reaction. How many times the rate of this catalysed reaction greater than that of uncatalysed reaction? \[(Given\,\,{{e}^{3.33}}=28)\]

    A) 15 times

    B) 38 times

    C) 22 times

    D) 28 times

    Correct Answer: D

    Solution :

    \[A\to B\] (uncatalysed reaction)
    \[A\xrightarrow{\text{catalyst}}B\] (catalyst reaction)
    \[K=A{{e}^{-{{E}_{a}}/RT}}\]
    \[{{K}_{\text{cat}\text{.}}}=A{{e}^{-{{E}_{a(cat.)}}/RT}}\]
    \[\frac{{{K}_{\text{cat}\text{.}}}}{K}={{e}^{({{E}_{a}}-E{{'}_{a}})\,\,\times \,\,\frac{1}{RT}}}\]
    \[\frac{{{K}_{\text{cat}\text{.}}}}{K}={{e}^{\frac{8.314\times {{10}^{3}}}{8.314\times 300}}}={{e}^{3.33}}=28\,\,\text{time}\]


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