NEET AIPMT SOLVED PAPER SCREENING 2008

  • question_answer
    The rate constants \[{{k}_{1}}\] and \[{{k}_{2}}\] for two different reactions are \[{{10}^{16}}.{{e}^{-2000/T}}\] and \[{{10}^{15}}.{{e}^{-1000/T}},\] respectively. The temperature at which \[{{k}_{1}}={{k}_{2}}\]is

    A) 1000 K                  

    B)        \[\frac{2000}{2.303}K\]                 

    C) 2000 K                                  

    D) \[\frac{1000}{2.303}K\]

    Correct Answer: D

    Solution :

    Key Idea: The Arrhenius equation is represented as\[k=A{{e}^{-{{E}_{a}}/RT}}\] In the given equations, first take log and. Then compare them. \[{{k}_{1}}={{10}^{16}}{{e}^{-2000/T}}\] \[{{k}_{2}}={{10}^{15}}{{e}^{-1000/T}}\]On taking log, we get \[\log {{k}_{1}}=\log {{10}^{16}}-\frac{2000}{2.303T}\]                    ?(i) \[\log {{k}_{2}}=\log {{10}^{15}}-\frac{1000}{2.303T}\]                    ?(ii) \[\because \]\[{{k}_{1}}={{k}_{2}}\]Hence, from Eqs (i) and (ii) \[T=\frac{1000}{2.303}K\]


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