JEE Main & Advanced Chemistry Chemical Kinetics / रासायनिक बलगतिकी Question Bank Rate law and Rate Constant

  • question_answer
    A first order reaction was started with a decimolar solution of the reactant, 8 minutes and 20 seconds later its concentration was found to be \[M/100\]. So the rate of the reaction is                [Kerala PMT 2004]

    A)                 \[2.303\times {{10}^{-5}}\ {{\sec }^{-1}}\]            

    B)                 \[2.303\times {{10}^{-4}}\ {{\sec }^{-1}}\]

    C)                 \[4.606\times {{10}^{-3}}\ {{\sec }^{-1}}\]

    D)                 \[2.606\times {{10}^{-5}}\ {{\sec }^{-1}}\]

    E)                 \[2.603\times {{10}^{-4}}\ {{\sec }^{-1}}\]

    Correct Answer: C

    Solution :

               For first order reaction \[K=\frac{2.303}{t}\log \frac{a}{a-x}\]                    Given: \[a=\frac{1}{10}=.1m\]; \[a-x=\frac{1}{100}=.01m\]; t = 500 sec                                 \[\therefore \ \ K=\frac{2.303}{500}\log \frac{.10}{.01}=\frac{2.303}{500}\log 10\] \[=\frac{2.303}{500}=0.004606=4.6\times {{10}^{-3}}{{\sec }^{-1}}\].       


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