MCQ
The reduction potential of hydrogen half-cell will be negative if :
  • A
    $p(H_2) = 1\,atm$ and $[H^+] = 2.0\,M$
  • B
    $p(H_2) = 1\,atm$ and $[H^+] = 1.0\,M$
  • $p(H_2) = 2\,atm$ and $[H^+] = 1.0\,M$
  • D
    $p(H_2) = 2\,atm$ and $[H^+] = 2.0\,M$

Answer

Correct option: C.
$p(H_2) = 2\,atm$ and $[H^+] = 1.0\,M$
c
$H^{+}+e^{-} \longrightarrow \frac{1}{2} H_{2}$

$E=E^{\circ}-\frac{0.059}{1} \log \frac{P_{H_{2}}^{1 / 2}}{\left|H^{+1}\right|}$

Now if $P_{H_{2}}=2$ atm and $\left[H^{+}\right]=1 M$

then $E=0-\frac{0.059}{1} \log \frac{2^{1 / 2}}{1}=-2$

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