JEE Main & Advanced AIEEE Solved Paper-2008

  • question_answer
    Given \[E_{C{{r}^{3+}}/Cr}^{o}=-0.72\,V,\,\,E_{F{{e}^{2+}}/Fe}^{o}=-0.42\,V\]. The potential for the cell \[Cr\left| C{{r}^{3+}}(0.1\,M)\, \right|\left| F{{e}^{2+}}(0.1\,M)\, \right|\] Fe is       AIEEE  Solved  Paper-2007

    A) - 0.339 V             

    B) - 0.26 V                

    C) 0.26 V   

    D) 0.339 V

    Correct Answer: C

    Solution :

    \[2Cr(s)+3F{{e}^{2+}}(aq)\xrightarrow{{}}2C{{r}^{3+}}(aq)+3Fe(s)\]        \[{{E}_{cell}}=E_{F{{e}^{2+}}\left| Fe \right.}^{o}-E_{C{{r}^{3+}}\left| Cr \right.}^{o}-\frac{0.0059}{6}\log \frac{{{[C{{r}^{3+}}]}^{2}}}{{{[F{{e}^{2+}}]}^{3}}}\]  \[=-0.42-(-0.72)-\frac{0.059}{6}\log \frac{{{(0.1)}^{2}}}{{{(0.01)}^{3}}}=0.26\,V\]


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