JEE Main & Advanced Sample Paper JEE Main - Mock Test - 11

  • question_answer
    At temperature of 298 K the emf of the following electrochemical cell \[A{{g}_{(s)}}|A{{g}^{+}}(0.1M)||Z{{n}^{2+}}(0.1M)|Z{{n}_{(s)}}\] will be (given \[E_{cell}^{{}^\circ }=-\,1.562\,V\])

    A) -1.532V

    B) -1.503V

    C) 1.532V             

    D) -3.06V

    Correct Answer: A

    Solution :

    [a] : \[2A{{g}_{(s)}}\xrightarrow[{}]{{}}2A{{g}^{+}}(0.1M)+2{{e}^{-}}\] \[2{{e}^{-}}+Z{{n}^{2+}}(0.1M)\xrightarrow[{}]{{}}Z{{n}_{(s)}}\] \[\underline{\overline{2A{{g}_{(s)}}+Z{{n}^{2+}}(0.1M)\xrightarrow[{}]{{}}2A{{g}^{+}}(0.1M)+Z{{n}_{(s)}}}}\] \[\therefore \]\[{{E}_{cell}}=E_{cell}^{o}-\frac{0.0591}{2}{{\log }_{10}}\frac{{{[A{{g}^{+}}]}^{2}}}{[Z{{n}^{2+}}]}\] \[\therefore \]\[{{E}_{cell}}=-1.562-\frac{0.0591}{2}{{\log }_{10}}\frac{{{(0.1)}^{2}}}{0.1}\] \[=-1.562-0.03{{\log }_{10}}{{10}^{-1}}\]  \[\Rightarrow \] \[{{E}_{cell}}=-1.562+0.03=-1.532V\] 


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