Question

The hydrogen electrode is dipped in a solution of $pH=3$ at $25{}^{\circ }C$. The potential would be:
(Take $\frac{2.303\times RT}{F}=0.059V)$

• A. $0.177V$
• B. $0.087V$
• C. $0.059V$
• D. $-0.177V$

Answer 1

The correct option is D $-0.177V$

Given,
$pH=3$
$\Rightarrow -log\left[H^{+}\right]=3$
$\Rightarrow \left[H^{+}\right]={10}^{-3}$
We know,
$E_{\text{red}}=E_{\text{red}}^0+0.059\log \left[H^{+}\right]\Rightarrow E=0+0.059\log {10}^{-3}\Rightarrow E=+0.059\times (-3)=-0.177V$