Question

A hydrogen gas electrode is made by dipping platinum wire in a solution of HCL of pH=10 and by passing hydrogen gas around the platinum wire at one atm pressure. The oxidation potential of electrode would be:
(a) 0.059 V
(b) 0.59 V
(c) 0.118 V
(d) 1.18 V

Answer 1

Hint: From pH value of solution, we can calculate the concentration of hydrogen ions in that solution. HCl dissociates completely in a solution.

Complete step-by-step answer:
HCl solution has a pH =10
So, we can calculate the concentration of hydrogen ions in the solution by taking a negative antilog of pH.
\[pH=-{{\log }_{10}}[{{H}^{+}}]\]
\[[{{H}^{+}}]={{10}^{-pH}}={{10}^{-10}}M\]
It is given that the pressure of hydrogen gas is 1 atmospheric pressure.

So the equation used is
\[{{E}_{cell}}=\dfrac{0.059}{n}\log \dfrac{{{({{P}_{{{H}_{2}}}})}^{0.5}}}{[{{H}^{+}}]}\]
Where \[{{E}_{cell}}\] is the electrode potential of the cell, \[{{P}_{{{H}_{2}}}}\]is the pressure of hydrogen gas, \[n\] is the number of moles, \[[{{H}^{+}}]\] is the concentration of \[{{H}^{+}}\].
Here, n=1 ,\[{{P}_{{{H}_{2}}}}\]=1 , \[[{{H}^{+}}]={{10}^{-pH}}={{10}^{-10}}M\]
Substituting these values in the equation, we get
\[{{E}_{cell}}=\dfrac{0.059}{1}\log \dfrac{1}{{{10}^{-10}}}=+0.59V\]

Therefore, the oxidation potential of electrodes is +0.59V. The correct option is (b).

Additional Information:
Hydrogen gas electrode is also called standard hydrogen electrode as it is used as a reference electrode based on the equilibrium between aqueous protons and electrons on one side and on hydrogen gas on the other side, in a solution saturated with hydrogen gas. It is a redox electrode abbreviated as SHE. It consists of a platinized platinum electrode which is dipped in an acidic solution (usually HCl) and pure hydrogen gas is bubbled through it. The acid solution should have an activity of \[{{H}^{+}}\] as \[1mold{{m}^{-3}}\]. There is a hydroseal which prevents oxygen interference.

Note: Oxidation potential of an electrode depends on the concentration of \[{{H}^{+}}\] and the pressure of the hydrogen gas. It also depends on the number of moles involved.