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


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