JEE Main & Advanced Chemistry Chemical Kinetics / रासायनिक बलगतिकी Sample Paper Topic Test - Chemical Kinetics

  • question_answer
    A reaction that is of the first order with respect to reactant A has a rate constant \[6{{\min }^{-1}}\]. If we start with [A]\[0.5\,mol\,{{l}^{-1}},\] when would [A] reach the value \[0.05\,mol\,{{l}^{-1}}\]

    A) 0.384 min

    B) 0.15 min

    C) 3 min               

    D) 3.84 min

    Correct Answer: A

    Solution :

    We know that for first order kinetics
    \[k=\frac{2.303}{t}\log \frac{a}{a-x},\left( a-x \right)=0.05mol\text{ }{{l}^{-1}}\]
    \[6=\frac{2.3030}{t}\log \frac{0.5}{0.05}\]
    or  \[t=\frac{2.303}{6}\log \frac{0.5}{0.05}=\frac{2.303}{6}=0.384\text{ }\min \]

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