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

Step 1: Why a reference electrode is required. 
The electrical potential of a single electrode cannot be measured on its own.
What can be measured experimentally is only the potential difference between two electrodes.
Hence, one electrode must be chosen as a fixed reference point to compare all others.

Step 2: Role of the Standard Hydrogen Electrode.
The Standard Hydrogen Electrode (SHE) is selected as this reference electrode.
It consists of an inert platinum electrode dipped in a 1 M acidic solution, with hydrogen gas supplied at 1 bar pressure and a temperature of 298 K.

By international convention, its electrode potential is defined as zero.
This allows the electrode potentials of all other half-cells to be measured relative to it.

The half-cell reaction for SHE is:

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

and its assigned standard potential is:

\[ E^\circ = 0.00 \text{ V} \]

Step 3: Final conclusion.
On the standard electrode potential scale, the Standard Hydrogen Electrode is defined to have a potential of zero volts.