JAMIA MILLIA ISLAMIA Jamia Millia Islamia Solved Paper-2010

  • question_answer
        In a reaction between A and B, the initial rate of reaction\[({{r}_{o}})\]was measured for different initial concentrations of A and B as given below
    \[A/mol\,{{L}^{-1}}\] 0.20 0.20 0.40
    \[B/mol\,{{L}^{-1}}\] 0.30 0.10 0.05
    \[{{r}_{0}}/\]\[mol\,{{L}^{-1}}{{s}^{-1}}\] \[5.07\times {{10}^{-5}}\] \[5.07\times {{10}^{-5}}\] \[1.43\times {{10}^{-4}}\]
    What is the order of the reaction with respect to A and B?

    A)  2.5, 1.0                

    B)  1.5,0

    C)  2.5,0                                    

    D)  1.5, 1

    Correct Answer: B

    Solution :

                    Rate\[=k{{[A]}^{p}}{{[B]}^{q}}\] \[Rat{{e}_{1}}={{(0.20)}^{p}}{{(0.30)}^{q}}=5.07\times {{10}^{-5}}\]      ... (i) \[Rat{{e}_{2}}={{(0.20)}^{p}}{{(0.10)}^{q}}=5.07\times {{10}^{-5}}\]     ... (ii)                 \[\frac{{{(0.30)}^{q}}}{{{(0.10)}^{q}}}=1\] \[{{3}^{q}}=1\]or\[{{3}^{q}}={{3}^{0}}\]\[\therefore \]\[q=0\] \[Rat{{e}_{3}}={{(0.40)}^{p}}{{(0.05)}^{q}}=1.43\times {{10}^{-4}}\]         ? (iii) Dividing (iii) by (i), we get                 \[\frac{{{(0.40)}^{p}}{{(0.05)}^{q}}}{{{(0.20)}^{p}}{{(0.10)}^{q}}}=\frac{1.43\times {{10}^{-4}}}{5.07\times {{10}^{-5}}}\]                 \[{{2}^{p}}\times \frac{1}{{{2}^{q}}}=2.8\] Since,            \[q=0\]                 \[{{2}^{p}}\times \frac{1}{{{2}^{0}}}=2.8\]                 \[{{2}^{p}}=2.8\]                 \[{{2}^{p}}={{(2)}^{1.5}}\] \[\therefore \]  \[p=1.5\] Thus, order of reaction w.r.t.\[A=1.5,\]and w.r.t. \[B=0\].


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