Question

The standard electrode potential of the standard hydrogen electrode (SHE) is:

• A. +1.00 V
• B. -1.00 V
• C. 0.00 V
• D. +0.76 V

Hint:

Any electrode with a positive standard reduction potential relative to SHE is a better oxidizing agent than \( H^+ \), while those with negative potentials are better reducing agents than \( H_2 \).

Answer 1

The Correct Option is C

To solve this question, we need to understand the concept of standard electrode potential, particularly for the standard hydrogen electrode (SHE).

Concept Explanation:

The standard hydrogen electrode (SHE) is used as a reference electrode in electrochemical cells. By convention, the potential of the SHE is defined as 0.00 volts under standard conditions. The SHE serves as a reference point for establishing the electrode potentials of other half-cells. The reaction at the SHE is as follows:

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

The SHE is defined as having a potential of 0.00 V at 25°C (298 K), 1 atm pressure, and a hydrogen ion concentration of 1 M. This convention allows other electrode potentials to be compared directly.

Analysis of Options:

1. +1.00 V: This value is not correct for the SHE; it represents other standard electrode potentials but not the SHE.
2. -1.00 V: This is incorrect, as it would imply an incorrect baseline potential for the SHE.
3. 0.00 V: This is correct, as per the definition of the SHE.
4. +0.76 V: This is the standard electrode potential for the zinc half-cell (Zn²⁺/Zn) under standard conditions, not the SHE.

Conclusion:

Therefore, the correct answer is 0.00 V, confirming that the standard electrode potential of the standard hydrogen electrode (SHE) is 0.00 V under standard conditions.

Answer 2

Step 1: Understanding the Concept:
The potential of a single electrode cannot be measured in isolation; only the difference in potential between two electrodes can be measured.
To create a relative scale, a reference electrode is needed.
Step 2: Detailed Explanation:
The Standard Hydrogen Electrode (SHE) is used as the universal reference electrode.
It consists of platinum foil in a 1M acidic solution with pure hydrogen gas bubbled at 1 bar pressure and 298 K temperature.
By convention (IUPAC agreement), the standard electrode potential of SHE is assigned the value of exactly zero volts at all temperatures.
\[ 2H^+(aq) + 2e^- \rightarrow H_2(g); \quad E^\circ = 0.00 \text{ V} \]
Step 3: Final Answer:
The standard electrode potential of SHE is 0.00 V.