JEE Main & Advanced Chemistry Chemical Kinetics / रासायनिक बलगतिकी Question Bank Critical Thinking Chemical Kinetics

  • question_answer
    The rate constant k, for the reaction \[{{N}_{2}}{{O}_{5}}(g)\to \] \[2N{{O}_{2}}(g)+\frac{1}{2}{{0}_{2}}(g)\] is \[2.3\times {{10}^{-2}}{{s}^{-1}}\]. Which equation given below describes the change of \[[{{N}_{2}}{{O}_{5}}]\] with time? \[{{[{{N}_{2}}{{O}_{5}}]}_{0}}\] and \[{{[{{N}_{2}}{{O}_{5}}]}_{t}}\]correspond to concentration of \[{{N}_{2}}{{O}_{5}}\]initially and at time, t          [AIIMS 2004]

    A)                 \[{{[{{N}_{2}}{{O}_{5}}]}_{t}}={{[{{N}_{2}}{{O}_{5}}]}_{0}}+kt\]

    B)                 \[{{[{{N}_{2}}{{O}_{5}}]}_{0}}={{[{{N}_{2}}{{O}_{5}}]}_{t}}{{e}^{kt}}\]

    C)                 \[{{\log }_{10}}{{[{{N}_{2}}{{O}_{5}}]}_{t}}={{\log }_{10}}{{[{{N}_{2}}{{O}_{5}}]}_{0}}-kt\]

    D)                 \[\text{In}\frac{{{\text{ }\!\![\!\!\text{ }{{\text{N}}_{\text{2}}}{{O}_{5}}]}_{0}}}{{{\text{ }\!\![\!\!\text{ }{{\text{N}}_{\text{2}}}{{O}_{5}}]}_{t}}}=kt\]

    Correct Answer: D

    Solution :

               Rate constant \[=2.3\times {{10}^{-2}}{{\sec }^{-1}}\]                    It means it is a first order reaction (because unit of rate constant is sec?1)                    For first order reaction \[K=\frac{1}{t}\ln \frac{a}{a-x}\]                                 \[Kt=\ln \frac{a}{a-x}=\ln \frac{{{[{{N}_{2}}{{O}_{5}}]}_{0}}}{{{[{{N}_{2}}{{O}_{5}}]}_{t}}}\] 


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