RAJASTHAN PMT Rajasthan - PMT Solved Paper-2003

  • question_answer
    In the first order reaction, half of the reaction is completed in 100 second. The time for 99% reaction to occur will be

    A)  \[664.64\text{ }sec\]     

    B)  \[646.6\text{ }sec\]

    C) \[660.9\text{ }sec~\]     

    D)  \[654.5\text{ }sec\]

    Correct Answer: A

    Solution :

    Half of the reaction is completed in 100 second \[\therefore \]  \[{{t}_{1/2}}=100\sec \] \[\therefore \]  \[K=\frac{0.693}{100}{{\sec }^{-1}}\] For a first order reaction                 \[K=\frac{2.303}{t}\log \frac{a}{a-x}\] \[a=100,\]           \[x=99,\]                              \[{{t}_{99%}}=?\]                 \[{{t}_{99%}}=\frac{2.303}{K}\log \frac{100}{100-99}\]                 \[=\frac{2.303\times 100}{0.693}\times \log 100\sec .\]                 \[=\frac{2.303\times 100\times 2}{0.693}\]                                 \[=664.64\sec .\]


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