Which of the following involves the reduction of copper?

Options

A. `Cu(s)+1//2O_(2)(g) rarr CuO(s)`
B. `Cu^( 2+)(aq)+2l^(-)(aq) rarr 2C"ul"(aq)`
C. `CuCl_(2)(s)+2F^(-)(aq) rarr CuF_(2)+Cl_(2)(g)`
D. `CuO+H_(2)O rarr Cu(OH)_(2)`

Answer

To determine which of the given reactions involves the reduction of copper, we will analyze each reaction step by step, focusing on the oxidation states of copper in each case.

### Step 1: Understand Reduction
Reduction is defined as the gain of electrons, which corresponds to a decrease in oxidation state.

### Step 2: Analyze the First Reaction
- **Reaction:** Cu + O2 → CuO
- **Oxidation States:**
- Cu (elemental) = 0
- O2 (elemental) = 0
- In CuO, O = -2, therefore Cu = +2.
- **Change in Oxidation State:** Cu goes from 0 to +2 (loss of electrons).
- **Conclusion:** This is oxidation, not reduction.

**Hint:** Check the oxidation states before and after the reaction to see if there is a gain or loss of electrons.

### Step 3: Analyze the Second Reaction
- **Reaction:** Cu^2+ + I^- → CuI
- **Oxidation States:**
- Cu^2+ = +2
- I^- = -1
- In CuI, I = -1, therefore Cu = +1.
- **Change in Oxidation State:** Cu goes from +2 to +1 (gain of electrons).
- **Conclusion:** This is reduction.

**Hint:** Look for a decrease in oxidation state to identify reduction.

### Step 4: Analyze the Third Reaction
- **Reaction:** CuCl2 + F2 → CuF2 + Cl2
- **Oxidation States:**
- In CuCl2, Cl = -1, thus Cu = +2.
- In CuF2, F = -1, thus Cu = +2.
- **Change in Oxidation State:** Cu remains at +2 (no change).
- **Conclusion:** No oxidation or reduction occurs.

**Hint:** If the oxidation state remains the same, neither oxidation nor reduction is taking place.

### Step 5: Analyze the Fourth Reaction
- **Reaction:** CuO + H2O → Cu + OH^-
- **Oxidation States:**
- In CuO, Cu = +2, O = -2.
- In Cu (elemental) = 0.
- **Change in Oxidation State:** Cu goes from +2 to 0 (gain of electrons).
- **Conclusion:** This is also reduction.

**Hint:** Compare the oxidation states of reactants and products to identify changes.

### Final Conclusion
The only reaction that involves the reduction of copper is the second reaction (Cu^2+ + I^- → CuI), where copper goes from +2 to +1, indicating a gain of electrons.

### Answer
The correct option that involves the reduction of copper is **Option 2**.