JEE Main & Advanced Chemistry Electrochemistry / विद्युत् रसायन Sample Paper Topic Test - Electrochemistry

  • question_answer
    The reduction potential of hydrogen half-cell will be negative if

    A) \[p({{H}_{2}})=2\,atm\,and\,[{{H}^{+}}]=2.0M\]

    B) \[p({{H}_{2}})=1\,atm\,and\,[{{H}^{+}}]=2.0M\]

    C) \[p({{H}_{2}})=1\,atm\,and\,[{{H}^{+}}]=1.0M\]

    D) \[p({{H}_{2}})=2\,atm\,and\,[{{H}^{+}}]=1.0M\]

    Correct Answer: D

    Solution :

    [d] For \[{{H}^{+}}(aq)+{{e}^{-}}\to (1/2){{H}_{2}}(g),\] we have
    \[E=-\frac{RT}{F}\ln \frac{{{\left( p{{H}_{2}}/atm \right)}^{1/2}}}{\left( [{{H}^{+}}]/M \right)}\]
    For E to be negative, the ratio \[\frac{{{\left( p{{H}_{2}}/atm \right)}^{1/2}}}{\left( [{{H}^{+}}]/M \right)}\] should be greater than 1. Only the choice ([d] produces this result.


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