JEE Main & Advanced Sample Paper JEE Main - Mock Test - 29

  • question_answer
    A second order reaction requires 70 min to change the concentration of reactants from \[0.08\text{ }M\]to\[0.01\text{ }M\]. The time required to become\[0.04\text{ }M=2x\text{ }min\]. Find the value of x.              

    A) \[5\]    

    B)                    \[6\]                   

    C) \[7\]                   

    D)        \[8\]

    Correct Answer: A

    Solution :

    [a] For second order reaction: \[{{[R]}_{initial}}=0.08\,M;\] \[{{[R]}_{final}}=0.01M\] \[x=0.08-0.01=0.07M\]\[\therefore \,\,\,\,(a-x)=0.08-0.07=0.01M\] \[{{k}_{2}}=\frac{1}{t}\frac{x}{a(a-x)}\] \[=\frac{1}{70\min }\times \frac{0.07M}{0.08M\times 0.01M}\]     ?.(i) Now, time required to become concentration \[=0.04M.\] i.e., \[x=0.04\text{ }M\] \[{{k}_{2}}=\frac{1}{t}\times \frac{0.04M}{0.08M\times (0.08-0.04)M}\] From Eqs. (i) and (ii) \[\frac{0.07}{70\times 0.08\times 0.01}=\frac{0.04}{t\times 0.08\times 0.04}\]        ?..(ii) \[t=10\min =2x\min \] \[\therefore \,\,\,\,x=5\min \]   


You need to login to perform this action.
You will be redirected in 3 sec spinner