`E^(@)` for `Cl_2`(g) `+2e^(-)to2Cl^-`(aq) is 1.36 V, `E^(@)` for `Cl^-` (aq) `to1//2cl_2`(g)`+e^-` is:

Options

A. 1.36V
B. -1.36V
C. -0.68
D. 0.68V

Answer

To solve the problem, we need to find the standard electrode potential (E°) for the half-reaction of Cl⁻ (aq) to 1/2 Cl₂ (g) + e⁻. We are given the standard electrode potential for the half-reaction of Cl₂ (g) + 2e⁻ to 2Cl⁻ (aq), which is E° = 1.36 V.

### Step-by-Step Solution:

1. **Understand the Given Reaction:**
The given reaction is:
\[ \text{Cl}_2(g) + 2e^- \rightarrow 2\text{Cl}^-(aq) \]
with E° = 1.36 V.

2. **Write the Reverse Reaction:**
We need to find the E° for the reverse reaction:
\[ 2\text{Cl}^-(aq) \rightarrow \text{Cl}_2(g) + 2e^- \]
According to the principles of electrochemistry, reversing a reaction changes the sign of the standard electrode potential. Therefore:
\[ E°_{\text{reverse}} = -E°_{\text{forward}} = -1.36 \text{ V} \]

3. **Divide the Reaction by 2:**
Since we want the half-reaction for Cl⁻ to 1/2 Cl₂, we divide the entire reaction by 2:
\[ \text{Cl}^-(aq) \rightarrow \frac{1}{2}\text{Cl}_2(g) + e^- \]
When we divide the reaction, the standard electrode potential remains the same:
\[ E° = -\frac{1.36 \text{ V}}{2} = -0.68 \text{ V} \]

4. **Final Result:**
Thus, the standard electrode potential for the half-reaction of Cl⁻ (aq) to 1/2 Cl₂ (g) + e⁻ is:
\[ E° = -0.68 \text{ V} \]

### Summary:
The standard electrode potential for the half-reaction Cl⁻ (aq) to 1/2 Cl₂ (g) + e⁻ is -0.68 V.

---