Which of the following processes does not involve oxidation of iron ?

Options

A. Rusting of iron sheets
B. Decolourisation of blue `CuSO_(4)` solution by iron
C. Formation of `Fe(CO)_(5)` from Fe
D. Liberation of `H_(2)` from steam by iron a high temperature.

Explanation

To determine which of the given processes does not involve the oxidation of iron, we will analyze each process step by step.

### Step 1: Analyze Rusting of Iron Sheets
- **Process A**: Rusting of iron sheets.
- **Reaction**: Iron (Fe) reacts with water (H2O) and oxygen (O2) to form rust, which is generally represented as Fe2O3·xH2O.
- **Oxidation States**:
- In elemental iron (Fe), the oxidation state is 0.
- In rust (Fe2O3), the oxidation state of iron can be calculated as follows:
- Let x be the oxidation state of iron.
- The equation for the oxidation state is: 2x + 3(-2) = 0 → 2x - 6 = 0 → 2x = 6 → x = +3.
- **Conclusion**: The oxidation state of iron changes from 0 to +3, indicating that oxidation has occurred.

### Step 2: Analyze Decolorization of Blue CuSO4 Solution by Iron
- **Process B**: Decolorization of blue CuSO4 solution by iron.
- **Reaction**: Fe + CuSO4 → FeSO4 + Cu (s).
- **Oxidation States**:
- In elemental iron (Fe), the oxidation state is 0.
- In iron(II) sulfate (FeSO4), the oxidation state of iron is +2.
- **Conclusion**: The oxidation state of iron changes from 0 to +2, indicating that oxidation has occurred.

### Step 3: Analyze Formation of Iron Carbonyl
- **Process C**: Formation of iron carbonyl.
- **Reaction**: Fe + CO → Fe(CO)5 (or similar complex).
- **Oxidation States**:
- In elemental iron (Fe), the oxidation state is 0.
- In iron carbonyl, the oxidation state of iron remains 0 (as CO is a neutral ligand).
- **Conclusion**: The oxidation state of iron does not change; it remains 0, indicating that no oxidation has occurred.

### Step 4: Analyze Reaction of Iron with Steam
- **Process D**: Reaction of iron with steam.
- **Reaction**: Fe + H2O (steam) → Fe3O4 + H2.
- **Oxidation States**:
- In elemental iron (Fe), the oxidation state is 0.
- In magnetite (Fe3O4), the oxidation state can be calculated:
- Let x be the oxidation state of iron.
- The equation for the oxidation state is: 3x + 4(-2) = 0 → 3x - 8 = 0 → 3x = 8 → x = +8/3 (which is approximately +2.67).
- **Conclusion**: The oxidation state of iron changes from 0 to approximately +2.67, indicating that oxidation has occurred.

### Final Conclusion
Based on the analysis, the process that does not involve the oxidation of iron is **Process C: Formation of Iron Carbonyl**.

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