Question

What will be the oxidation potential for the following hydrogen half cell at $1$ bar pressure and $25^{\circ} C$ temperature ?
$Pt \left| H _{2( g )}\right| HCl ( aq )$ when $pH =3$ and pressure of $H _{2}$ gas is $1$ bar.

• A. 0.059 V
• B. 0.188 V
• C. 0.177 V
• D. 0.000 V

Answer 1

Answer: (C)

For oxidation
$\frac{1}{2} H_{2}(g) \rightarrow H^{+}(a q)+e^{-}$
$P=1\, atm $
$E_{O P}=E_{O P}^{\circ}-\frac{0.059}{1} \log \left[H^{+}\right] $
$E_{O P}=0+0.059 p H$
$=0.059 \times 3=0.177\, V$