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BCECE Engineering BCECE Engineering Solved Paper-2010

  • question_answer
    Consider the following \[{{\text{E}}^{\text{o}}}\]values \[E_{F{{e}^{3+}}/F{{e}^{2+}}}^{o}=+\,0.77\,V\] \[E_{S{{n}^{2+}}/Sn}^{o}=-0.14\,V\] Under standard conditions the potential for the reaction, \[Sn(s)+2F{{e}^{3+}}(aq)\xrightarrow{{}}2F{{e}^{2+}}(aq)+S{{n}^{2+}}(aq)\]is

    A)  1.68 V                                  

    B)  1.40 V  

    C)         0.91 V                                  

    D)  0.63 V

    Correct Answer: C

    Solution :

    \[Sn(s)+2F{{e}^{3+}}(aq)\xrightarrow{{}}2F{{e}^{2+}}(aq)+S{{n}^{2+}}(aq)\]       \[E_{cell}^{o}=E_{ox}^{o}+E_{red}^{o}\]              \[=E_{Sn/S{{n}^{2+}}}^{o}+E_{F{{e}^{3+}}/F{{e}^{2+}}}^{o}\] Given,  \[E_{S{{n}^{2+}}/Sn}^{o}=-0.14\,V\] \[\therefore \]  \[E_{Sn/s{{n}^{2+}}}^{o}=+0.14\,V\] \[E_{F{{e}^{3+}}/F{{e}^{2+}}}^{o}=0.77\,V\]                 \[\therefore \]  \[E_{cell}^{o}=0.14+0.77=0.91\,V\]


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