J & K CET Engineering J and K - CET Engineering Solved Paper-2012

  • question_answer
    Standard electrode potential of half-cell reactions are given below \[C{{u}^{2+}}+2{{e}^{-}}\xrightarrow{{}}Cu;\] \[{{E}^{o}}=0.34\,V\] \[Z{{n}^{2+}}+2{{e}^{-}}\xrightarrow{{}}Zn;\] \[{{E}^{o}}=-\,0.76\,V\] What is the emf of the cell?

    A) \[~+\text{ }1.10\,V\]        

    B) \[-1.10\,V\]

    C) \[-0.42\,V\]         

    D) \[+\,0.42\,V\]

    Correct Answer: A

    Solution :

     \[Zn\xrightarrow{{}}Z{{n}^{2+}}+2{{e}^{-}}\]  (oxidation half-reaction) \[C{{u}^{2+}}+2{{e}^{-}}\xrightarrow{{}}Cu\](reduction half-reaction) Emf of the cell = standard oxidation potential of zinc electrode + standard reduction potential of Cu electrode \[=0.76\text{ }V+0.34\,V\] \[=1.10\,V\]


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