Q25 / 160 · TS EAMCET 2018 (05 May Shift 2) · Chemistry

The potential of hydrogen electrode of $\mathrm{pH}=10$ with respect to standard hydrogen electrode is

  • A
    $-0.0591 \mathrm{~V}$
  • Correct answer
    B
    $-0.591 \mathrm{~V}$
  • C
    $0.2 \mathrm{~V}$
  • D
    0

Solution

For, hydrogen electrode $$ \mathrm{pH}=10 \quad\left[\mathrm{H}^{+}\right]=10^{-10} \mathrm{M} \quad \mathrm{H}^{+}+e^{-}=\frac{1}{2} \mathrm{H}_2 $$ $$ \begin{aligned} & E_{\text {cell }}=E^{\circ}-\frac{0.0591}{1} \log \frac{\left[\mathrm{H}_2\right]}{\left[\mathrm{H}^{+}\right]} \\ & E^{\circ}=0 ; \log \mathrm{H}_2=0 \text { because } \\ & E_{\text {cell }}=-\frac{0.0591}{1} \log \left(\frac{1}{10^{-10}}\right)-0.0591 \times 10 \\ & E_{\text {cell }}=-0.591 \mathrm{~V} \end{aligned} $$

Hence, the correct answer is option: 'B'.

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