Question

A hydrogen gas. electron is made by dipping platinum wire in a solution of$HCI$ of $pH=10$ and by passing hydrogen gas around the platinum wire at one atm pressure.The oxidation potential of electrode would be ?

• A. $1.18V$
• B. $0.059V$
• C. $-0.59V$
• D. $0.118V$

Answer 1

The correct option is C $-0.59V$

Given $pH=10$

$\Rightarrow pH=-\log \left[H^{+}\right]$

$\Rightarrow 10=-\log \left[H^{+}\right]$

$\Rightarrow \left[H^{+}\right]={10}^{-10}$ .

Nernst equation: $E_{cell}=E_{cell}^o-\frac{9.303}{np}RT\log \left[\frac{H_2}{H^{+}}\right]$

$H^{+}+e^{-}⟶\frac{1}{2}{H_2}_{\left(g\right)}$ For this $E_{cell}^o=0V$

$n=1,\frac{RT}{F}=0.0591$

So $E_{cell}=0-0.0591\log \left(\frac{1}{{10}^{-10}}\right)$

$=-0.0591\times 10$

$=-0.591V$.