`FeS+KMnO_(4)+H_(2)SO_(4)rarr Fe_(2)(SO_(4))_(3)+K_(2)SO_(4)`. The equivalent mass `FeS` in the above reaction is :

Options

A. `("Mol wt.")/(1)`
B. `("Mol wt.")/(3)`
C. `("Mol wt.")/(3)`
D. `("Mol wt.")/(9)`

Answer

To find the equivalent mass of FeS in the reaction given, we will follow these steps:

### Step 1: Write the balanced chemical equation
The reaction is given as:
\[ \text{FeS} + \text{KMnO}_4 + \text{H}_2\text{SO}_4 \rightarrow \text{Fe}_2(\text{SO}_4)_3 + \text{K}_2\text{SO}_4 \]

### Step 2: Determine the oxidation states
- In FeS, the oxidation state of Fe is +2 (since S is -2).
- In \(\text{Fe}_2(\text{SO}_4)_3\), the oxidation state of Fe is +3 (since SO4 has a charge of -2).

### Step 3: Calculate the change in oxidation state for Iron (Fe)
- Change in oxidation state for Fe:
\[ +3 - (+2) = +1 \]
This means Fe loses 1 electron.

### Step 4: Determine the oxidation state of Sulfur (S)
- In FeS, S is -2.
- In \(\text{Fe}_2(\text{SO}_4)_3\), the oxidation state of S is +6.

### Step 5: Calculate the change in oxidation state for Sulfur (S)
- Change in oxidation state for S:
\[ +6 - (-2) = +8 \]
This means S loses 8 electrons.

### Step 6: Calculate the total change in oxidation state for FeS
- Total change in oxidation state for FeS:
\[ +1 \text{ (from Fe)} + +8 \text{ (from S)} = +9 \]

### Step 7: Calculate the equivalent mass of FeS
- The equivalent mass is given by the formula:
\[ \text{Equivalent mass} = \frac{\text{Molecular weight of FeS}}{\text{Total change in oxidation state}} \]

### Step 8: Find the molecular weight of FeS
- The molecular weight of FeS:
- Iron (Fe) = 55.85 g/mol
- Sulfur (S) = 32.07 g/mol
- Molecular weight of FeS = 55.85 + 32.07 = 87.92 g/mol

### Step 9: Substitute into the equivalent mass formula
- Substitute the values:
\[ \text{Equivalent mass of FeS} = \frac{87.92 \text{ g/mol}}{9} \approx 9.77 \text{ g/equiv} \]

### Conclusion
The equivalent mass of FeS in the reaction is approximately **9.77 g/equiv**.

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