NEET Chemistry NEET PYQ-Electrochemistry

  • question_answer
    A hydrogen gas electrode is made by dipping platinum wire in a solution of \[HCl\] of \[pH=10\] and by passing hydrogen gas around the platinum wire at 1 atm pressure. The oxidation potential of electrode would be        [NEET 2013]

    A) 0.059 V

    B) 0.59 V

    C) 0.118 V

    D) 1.18 V

    Correct Answer: B

    Solution :

    [b] For hydrogen electrode, oxidation half reaction is
    \[\underset{(1\,atm)}{\mathop{{{H}_{2}}}}\,\xrightarrow[{}]{{}}\underset{(At\,pH\,10)}{\mathop{2{{H}^{+}}}}\,+2{{e}^{-}}\]
    If          \[pH=10\]
                \[{{H}^{+}}=1\times {{10}^{-pH}}=1\times {{10}^{-10}}\]
    From Nernst equation,
    \[{{E}_{cell}}={{E}^{o}}_{cell}=\frac{0.0591}{2}\log \frac{{{[{{H}^{+}}]}^{2}}}{{{p}_{{{H}_{2}}}}}\]
    For hydrogen electrode \[{{E}^{o}}_{cell}=0\]
    \[{{E}_{cell}}=-\frac{0.0591}{2}\log \frac{{{({{10}^{-10}})}^{2}}}{1}\]
    \[=+\frac{0.0591\times 2}{2}\log \frac{1}{{{10}^{-10}}}\]
    \[=0.0591\,\log \,{{10}^{10}}\]
    \[=0.059\times 10=0.591\,V\]


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