NEET AIPMT SOLVED PAPER 2003

  • question_answer
                    The emf of a Daniell cell at 298 K is \[{{E}_{1}}\]                                                                                                                              \[ZN\,\left| \begin{align}   & ZnS{{O}_{4}} \\  & (0.01\,M) \\ \end{align} \right|\,\left| \begin{align}   & CuS{{O}_{4}} \\  & (1.0\,M) \\ \end{align} \right|Cu\]                 When the concentration of \[ZnS{{O}_{4}}\] is 1.0M and that of \[CuS{{O}_{4}}\] is 0.01 M, the emf changed to \[{{E}_{2}}\]. What is the relationship between \[{{E}_{1}}\] and \[{{E}_{2}}\]?

    A)                 \[{{E}_{1}}={{E}_{2}}\]                         

    B)                 \[{{E}_{2}}=0\,\ne {{E}_{1}}\]                             

    C)                 \[{{E}_{1}}>E{{ & }_{2}}\]                    

    D)                 \[{{E}_{1}}<{{E}_{2}}\]

    Correct Answer: C

    Solution :

                    For Daniell cell                 \[Zn\left| \begin{align}   & ZnS{{O}_{4}} \\  & 0.01\,M \\ \end{align} \right|\,\,\,\,\,\,\,\,\,\,\,\,\,\left| \begin{align}   & CuS{{O}_{4}} \\  & 1.0\,M \\ \end{align} \right|\,\,Cu\]                 Cell reaction is                 \[Zn(s)+C{{u}^{2+}}(aq)\rightleftharpoons Cu(s)+Z{{n}^{2+}}(aq)\]                 For above cell                 \[{{E}_{1}}={{E}^{o}}_{cell}-\frac{0.0591}{n}{{\log }_{10}}\frac{[Z{{n}^{2+}}]}{[Cu]}\]                 \[{{E}_{1}}=E_{cell}^{o}-\frac{0.0591}{2}{{\log }_{10}}\frac{0.01}{1.0}\]                 \[{{E}_{1}}=E_{cell}^{o}-\frac{0.0591}{2}{{\log }_{10}}\frac{1}{100}\]                 \[=E_{cell}^{o}+0.0591\,\,\,{{\log }_{10}}\,10\]                 \[=E_{cell}^{o}+0.0591\]                    ....(i)                 When the concentration of \[Z{{n}^{2+}}\] is 1.0 M and concentration of \[C{{u}^{2+}}\,\]is 0.01 M                 \[{{E}_{2}}=E_{cell}^{o}-\frac{0.0591}{2}{{\log }_{10}}\frac{1}{0.01}\]                 \[=E_{cell}^{o}-\frac{0.0591}{2}{{\log }_{10}}{{10}^{2}}\]                 \[=E_{cell}^{o}-0.0591....(ii)\]                 From Eqs. (i) and (ii) \[{{E}_{1}}>{{E}_{2}}\]


You need to login to perform this action.
You will be redirected in 3 sec spinner