JEE Main & Advanced Sample Paper JEE Main - Mock Test - 37

  • question_answer
    The reaction: \[OC{{l}^{\Theta }}+{{I}^{^{\Theta }}}\xrightarrow{\overset{^{\Theta }}{\mathop{O}}\,H}+C{{l}^{^{\Theta }}}\] Takes place in the following steps:
    (i) \[OC{{l}^{\Theta }}+{{H}_{2}}OHOCl+\overset{\Theta }{\mathop{O}}\,H\,\,(fast)\]
    (ii) \[{{I}^{\Theta }}+HOCl\xrightarrow{{{k}_{3}}}HOI+C{{l}^{\Theta }}\,\,(slow)\]
    (iii) \[\overset{\Theta }{\mathop{O}}\,H+HOI{{H}_{2}}O+O{{I}^{\Theta }}\,(fast)\]
    The rate of consumption of \[{{I}^{\Theta }}\] in the following equation is:

    A) \[\frac{{{k}_{3}}{{k}_{1}}}{{{k}_{2}}}\frac{[OC{{l}^{\Theta }}][{{I}^{\Theta }}]}{[\overset{\Theta }{\mathop{O}}\,H]}\]

    B)        \[\frac{{{k}_{1}}{{k}_{2}}}{{{k}_{3}}}\frac{[OC{{l}^{\Theta }}][{{I}^{\Theta }}]}{[\overset{\Theta }{\mathop{O}}\,H]}\]

    C) \[\frac{{{k}_{1}}{{k}_{3}}}{{{k}_{2}}}\frac{[OC{{l}^{\Theta }}][{{I}^{\Theta }}]}{[\overset{\Theta }{\mathop{O}}\,H]}\]

    D)        \[\frac{{{k}_{2}}{{k}_{3}}}{{{k}_{1}}}\frac{[OC{{l}^{\Theta }}][{{I}^{\Theta }}]}{[\overset{\Theta }{\mathop{O}}\,H]}\]

    Correct Answer: C

    Solution :

    [c] Step (ii) is the rate-determining step. \[\therefore \] Rate  \[{{k}_{3}}[{{I}^{\Theta }}]\,\,[HOCl]\]           ....(l) \[(HOCl)\] produced in step (i) is consumed in step (ii), so it is a reactive intermediate. Similary, \[(HOI)\] produced in step (ii) is consumed in step (iii). so it is also a reactive intermediate. The concentration of both reactive species is determined from their equilibrium constant value. \[\therefore \]  From step (i) \[\frac{{{k}_{1}}}{{{k}_{2}}}=\frac{[HOCl]\,[\overset{\Theta }{\mathop{O}}\,H]}{[OC{{l}^{\Theta }}]}\Rightarrow [HOCl]=\frac{{{k}_{1}}}{{{k}_{2}}}\frac{[OC{{l}^{\Theta }}]}{[\overset{\Theta }{\mathop{O}}\,H]}\]   ?.(2) Substitute the value of \[[HOCl]\]from Eq. (2) in Eq. Rate \[=\frac{{{k}_{1}}{{k}_{3}}}{{{k}_{2}}}\frac{[OC{{l}^{\Theta }}][{{I}^{\Theta }}]}{[\overset{\Theta }{\mathop{O}}\,H]}\] Hence answer is (3).


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