JCECE Engineering JCECE Engineering Solved Paper-2005

  • question_answer
    What is potential of platinum wire dipped into a solution of \[0.1\,\,M\]in\[S{{n}^{2+}}\] and \[0.01\,\,M\] in\[S{{n}^{4+}}\]?

    A) \[{{E}_{0}}\]                                      

    B) \[{{E}_{0}}+0.059\]

    C) \[{{E}_{0}}+\frac{0.059}{2}\]                      

    D)  \[{{E}_{0}}=\frac{0.059}{2}\]

    Correct Answer: D

    Solution :

    Key Idea: \[{{E}_{cell}}=E_{cell}^{\text{o}}+\frac{0.059}{n}\log \left[ \frac{product}{reactant} \right]\]                 \[S{{n}^{2+}}\xrightarrow{{}}S{{n}^{4+}}+2{{e}^{-}}\] \[\therefore \]  \[n=2\] Given\[[S{{n}^{2+}}]=0.1\,\,M,\,\,[S{{n}^{4+}}]=0.01\,\,M\]                 \[{{E}_{cell}}=E_{cell}^{o}+\frac{0.059}{2}\log \left[ \frac{S{{n}^{4+}}}{S{{n}^{2+}}} \right]\]                         \[=E_{cell}^{o}+\frac{0.059}{2}\log \left[ \frac{0.01}{0.1} \right]\]                        \[=E_{cell}^{o}+\frac{0.059}{2}\log 0.1\]                       \[=E_{cell}^{o}+\frac{0.059}{2}\times -1\]                      \[=E_{cell}^{o}+\frac{0.059}{2}\]


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