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. 1.81 V
• B. 0.059 V
• C. 0.59 V
• D. 0.118 V

Answer 1

The Correct Option is C

To solve this problem, we need to determine the oxidation potential of the hydrogen gas electrode when placed in a solution with a given pH. The standard hydrogen electrode (SHE) potential is given as 0 V by convention. The electrode reaction for the hydrogen electrode is:

2H^+ + 2e^- \rightarrow H_2(g)

The Nernst Equation for the electrode potential in reference to SHE is:

E = E^0 - \frac{0.059}{n} \log \frac{[H_2]}{[H^+]^2}

where:

• E^0 is the standard electrode potential, for the hydrogen electrode (E^0 = 0 \text{ V}).
• \frac{0.059}{n} is the value for 298 K (25°C), where n is the number of electrons (2 for this reaction).
• [H_2] is the pressure of hydrogen, at 1 atm here.
• [H^+] is the concentration of hydrogen ions.

Given the pH is 10, we calculate [H^+] using:

[H^+] = 10^{-pH} = 10^{-10}

Substitute these values into the Nernst Equation:

E = 0 - \frac{0.059}{2} \log \frac{1}{(10^{-10})^2}

Simplifying, we get:

E = -0.059 \log (10^{20})

E = -0.059 \times 20

E = -1.18 \text{ V}

The question asks for the oxidation potential, which is the negative of the electrode potential.

Therefore, the oxidation potential is:

0.59 \text{ V}

Thus, the correct answer is 0.59 V.