NEET Chemistry NEET PYQ-Chemical Kinetics

  • question_answer
    The rate of reaction \[2{{N}_{2}}{{O}_{5}}\xrightarrow[{}]{{}}4N{{O}_{2}}+{{O}_{2}}\]can be written in three ways
    \[\frac{-d[{{N}_{2}}{{O}_{5}}]}{dt}=k[{{N}_{2}}{{O}_{5}}]\]            \[\frac{d[NO_{7}^{2}]}{dt}=k'[{{N}_{2}}{{O}_{5}}]\]
    \[\frac{d[O_{2}^{{}}]}{dt}=k''[{{N}_{2}}{{O}_{5}}]\]    [AIPMT (M) 2011]
    The relationship between k and k' and between k’’ and k'' are

    A) k’ = 2 k; k’ = k

    B) k’ = 2k; k’’=k/2

    C) k’ = 2k; k’’ = 2k

    D) k’ = k; k’’ = k

    Correct Answer: B

    Solution :

    [b] Rate \[=-\frac{1}{2}\frac{d[{{N}_{2}}{{O}_{5}}]}{dt}=\frac{1}{4}\frac{d[N{{O}_{2}}]}{dt}=\frac{d[{{O}_{2}}]}{dt}\]
    \[\Rightarrow \]\[\frac{1}{2}k[{{N}_{2}}{{O}_{5}}]=\frac{1}{4}k'[{{N}_{2}}{{O}_{5}}]=k'\,'[{{N}_{2}}{{O}_{5}}]\]
    \[\Rightarrow \]   \[\frac{k}{2}=\frac{k'}{4}=k'\,'\]
    \[\therefore \]      \[k'=2k;k'\,'=\frac{k}{2}\]


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