For the disproportion of copper:
`2 Cu^(+) to Cu^(+2) + Cu E^(0)` is :- Given `E^(0)` for `Cu^(+2)//Cu` is 0.34 V & `E^(0)` for `Cu^(+2)//Cu^(+)` is 0.15 V:

Options

A. 0.49 V
B. `-0.19V`
C. 0.38 V
D. `-0.38 V`

Answer

To solve the problem of calculating the standard electrode potential (E°) for the disproportionation of copper, we need to analyze the given half-reactions and their respective standard electrode potentials.

### Step-by-Step Solution:

1. **Identify the Half-Reactions**:
The disproportionation reaction given is:
\[ 2 \text{Cu}^+ \rightarrow \text{Cu}^{2+} + \text{Cu} \]
We can break this down into two half-reactions:
- Half-reaction 1: \(\text{Cu}^{2+} + 2e^- \rightarrow 2\text{Cu}\) with \(E^\circ = +0.34 \, \text{V}\)
- Half-reaction 2: \(\text{Cu}^+ + e^- \rightarrow \text{Cu}\) with \(E^\circ = ?\) (we will calculate this)

2. **Use Given Values**:
We know:
- \(E^\circ\) for \(\text{Cu}^{2+} + e^- \rightarrow \text{Cu}^+\) is \(0.15 \, \text{V}\).
- We need to find \(E^\circ\) for the half-reaction \(\text{Cu}^+ + e^- \rightarrow \text{Cu}\).

3. **Calculate \(E^\circ\) for \(\text{Cu}^+ + e^- \rightarrow \text{Cu}\)**:
Using the relationship:
\[ \Delta G^\circ = -nFE^\circ \]
For the reaction \(\text{Cu}^{2+} + 2e^- \rightarrow 2\text{Cu}\):
\[ \Delta G^\circ = -2F \cdot 0.34 \]
For the reaction \(\text{Cu}^{2+} + e^- \rightarrow \text{Cu}^+\):
\[ \Delta G^\circ = -F \cdot 0.15 \]
We can relate these two:
\[ -2F \cdot 0.34 = -F \cdot 0.15 + -F \cdot E^\circ \]
Simplifying gives:
\[ 2 \cdot 0.34 = 0.15 + E^\circ \]
\[ 0.68 - 0.15 = E^\circ \]
\[ E^\circ = 0.53 \, \text{V} \]

4. **Combine the Half-Reactions**:
Now, we have:
- Half-reaction 1 (reversed): \(\text{Cu}^+ \rightarrow \text{Cu}^{2+} + e^-\) with \(E^\circ = -0.15 \, \text{V}\)
- Half-reaction 2: \(\text{Cu}^+ + e^- \rightarrow \text{Cu}\) with \(E^\circ = 0.53 \, \text{V}\)

5. **Calculate the Overall E° for the Disproportionation Reaction**:
Now we can add the potentials:
\[ E^\circ_{\text{total}} = (-0.15) + (0.53) = 0.38 \, \text{V} \]

### Final Answer:
The standard electrode potential (E°) for the disproportionation of copper is:
\[ \boxed{0.38 \, \text{V}} \]