JEE Main & Advanced JEE Main Paper (Held On 26 May 2012)

  • question_answer
    Given\[E_{C{{u}^{2+}}/Cu}^{o}=0.34V,E_{C{{u}^{2+}}/Cu}^{o}=0.15V\] Standard electrode potential for the half cell \[C{{u}^{+}}/Cu\]is.   JEE Main Online Paper (Held On 26-May-2012)  

    A) 0.38V                                    

    B)                        0.53V

    C)                        0.19V                                    

    D)                        0.49V

    Correct Answer: B

    Solution :

                    \[C{{u}^{++}}+{{e}^{-}}\xrightarrow[{}]{{}}C{{u}^{+}}\] \[E_{1}^{0}=0.15V;\Delta G_{1}^{0}=-{{n}_{1}}E_{1}^{0}F\] \[C{{u}^{2+}}+2e\xrightarrow[{}]{{}}Cu\] \[E_{2}^{0}=0.34V;\Delta G_{2}^{0}=-{{n}_{2}}E_{2}^{0}F\] On subracting eq.(i) from eq. (ii) we get \[C{{u}^{+}}+{{e}^{-}}\xrightarrow[{}]{{}}Cu;\Delta {{G}^{0}}=\Delta G_{2}^{0}-\Delta G_{1}^{0}\] \[-n{{E}^{0}}F=-({{n}_{2}}{{E}^{0}}F-{{n}_{1}}F_{1}^{2}F)\] \[{{E}^{0}}=\frac{{{n}_{2}}E_{2}^{0}F-{{n}_{1}}E_{1}^{0}F}{nF}\] \[=\frac{2\times 0.34-0.15}{1}\]                \[=0.53V\]


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