`FeCr_(2)O_(4)+Na_(2)CO_(3)+O_(2) to Fe_(2)O_(3)darr+Na_(2)CrO_(4)`

Options

A. For disproportionation reaction.
B. For comproportionation reaction.
C. For either intermolecular redox reaction or displacement reaction
D. For either thermal combination redox reaction or thermal decomposition redox reaction.

Answer

To analyze the reaction \( \text{FeCr}_2\text{O}_4 + \text{Na}_2\text{CO}_3 + \text{O}_2 \rightarrow \text{Fe}_2\text{O}_3 + \text{Na}_2\text{CrO}_4 \), we will follow these steps:

### Step 1: Determine the oxidation states of each element in the reactants and products.

1. **For \( \text{FeCr}_2\text{O}_4 \)**:
- Oxygen (O) has an oxidation state of -2.
- Let the oxidation state of Fe be \( x \) and that of Cr be \( y \).
- The compound is neutral, so:
\[ x + 2y + 4(-2) = 0 \implies x + 2y - 8 = 0 \implies x + 2y = 8 \quad (1) \]
- Since \( \text{Cr}_2\text{O}_4^{2-} \) has a total oxidation state of -2, we can say:
\[ 2y - 8 = -2 \implies 2y = 6 \implies y = +3 \]
- Substituting \( y \) back into equation (1):
\[ x + 2(3) = 8 \implies x + 6 = 8 \implies x = +2 \]
- Thus, \( \text{Fe} = +2 \) and \( \text{Cr} = +3 \).

2. **For \( \text{Na}_2\text{CO}_3 \)**:
- Sodium (Na) has an oxidation state of +1.
- Carbon (C) has an oxidation state of +4.
- Oxygen (O) has an oxidation state of -2.
- The oxidation states are: \( \text{Na} = +1, \text{C} = +4, \text{O} = -2 \).

3. **For \( \text{Fe}_2\text{O}_3 \)**:
- Oxygen has an oxidation state of -2.
- Let the oxidation state of Fe be \( x \).
- The compound is neutral:
\[ 2x + 3(-2) = 0 \implies 2x - 6 = 0 \implies 2x = 6 \implies x = +3 \]
- Thus, \( \text{Fe} = +3 \).

4. **For \( \text{Na}_2\text{CrO}_4 \)**:
- Sodium (Na) has an oxidation state of +1.
- Let the oxidation state of Cr be \( z \).
- The compound is neutral:
\[ 2(+1) + z + 4(-2) = 0 \implies 2 + z - 8 = 0 \implies z = +6 \]
- Thus, \( \text{Cr} = +6 \).

### Step 2: Identify oxidation and reduction.

- **Oxidation**: Increase in oxidation state.
- Fe changes from +2 to +3 (oxidation).
- Cr changes from +3 to +6 (oxidation).

- **Reduction**: Decrease in oxidation state.
- O changes from 0 to -2 (reduction).

### Step 3: Classify the reaction.

- Since both Fe and Cr are undergoing oxidation, and oxygen is undergoing reduction, this reaction does not fit the definition of a disproportionation or comproportionation reaction.

- The reaction involves multiple species and can be classified as an **intermolecular redox reaction** because it involves the transfer of electrons between different molecules.

### Conclusion:
The correct classification of the reaction \( \text{FeCr}_2\text{O}_4 + \text{Na}_2\text{CO}_3 + \text{O}_2 \rightarrow \text{Fe}_2\text{O}_3 + \text{Na}_2\text{CrO}_4 \) is **intermolecular redox reaction**.

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