Question:medium

Which of the following reactions exhibit minimum standard reduction potential?

Show Hint

Alkali metals usually have very negative reduction potentials, so they are strong reducing agents in elemental form.
Updated On: May 14, 2026
  • \(2\text{H}^+_{\text{(aq)}} + 2\text{e}^- \rightarrow \text{H}_{2\text{(g)}}\)
  • \(\text{F}_{2\text{(g)}} + 2\text{e}^- \rightarrow 2\text{F}^-_{\text{(aq)}}\)
  • \(\text{Li}^+_{\text{(aq)}} + \text{e}^- \rightarrow \text{Li}_{\text{(s)}}\)
  • \(\text{Cl}_{2\text{(g)}} + 2\text{e}^- \rightarrow 2\text{Cl}^-_{\text{(aq)}}\)
Show Solution

The Correct Option is C

Solution and Explanation

Step 1: Understanding the Concept:
The standard reduction potential (\(E^\circ\)) measures the tendency of a chemical species to be reduced (gain electrons).
A highly positive \(E^\circ\) value indicates a strong tendency to gain electrons (strong oxidizing agent).
A highly negative \(E^\circ\) value indicates a strong tendency to lose electrons when the reaction is reversed, meaning the reduced form is a strong reducing agent.
The question asks for the "minimum" standard reduction potential, which means the most negative value on the electrochemical series.
Step 2: Key Formula or Approach:
Recall the position of each element in the electrochemical series.
The minimum (most negative) standard reduction potential corresponds to the strongest reducing agent in its reduced form.
Step 3: Detailed Explanation:
Let's recall the relative positions of these half-reactions in the standard electrochemical series:
(A) The reduction of Hydrogen ions to Hydrogen gas is chosen as the standard reference half-cell.
Its standard reduction potential is defined as exactly \(E^\circ = 0.00 \text{ V}\).
(B) Fluorine gas (\(\text{F}_2\)) is the most electronegative element and the strongest oxidizing agent in the periodic table.
It has the highest positive standard reduction potential (\(E^\circ \approx +2.87 \text{ V}\)).
(D) Chlorine gas (\(\text{Cl}_2\)) is a halogen and a strong oxidizing agent, though weaker than fluorine.
It has a positive standard reduction potential (\(E^\circ \approx +1.36 \text{ V}\)).
(C) Lithium metal (\(\text{Li}\)) is the strongest reducing agent in aqueous solution among all elements due to its high hydration energy.
Consequently, the reduction of its ion, \(\text{Li}^+\), is highly unfavorable.
It occupies the very bottom of the electrochemical series with the lowest (most negative) standard reduction potential (\(E^\circ \approx -3.05 \text{ V}\)).
Comparing these values, the Lithium reduction reaction has the most negative, hence minimum, standard reduction potential.
Step 4: Final Answer:
The reaction involving Lithium exhibits the minimum standard reduction potential.
Was this answer helpful?
0