`FeS to Fe^(3+) + SO_(3)`
Eq. wt. of FeS for this change is (mol. Wt. of FeS=M)

Options

A. `M/1`
B. `M/5`
C. `M/7`
D. `M/9`

Answer

To determine the equivalent weight of FeS for the reaction \( \text{FeS} \rightarrow \text{Fe}^{3+} + \text{SO}_3 \), we will follow these steps:

### Step 1: Write the balanced equation
The reaction can be represented as:
\[ \text{FeS} \rightarrow \text{Fe}^{3+} + \text{SO}_3 \]

### Step 2: Determine the oxidation states
- In FeS, iron (Fe) has an oxidation state of +2, and sulfur (S) has an oxidation state of -2.
- In \(\text{Fe}^{3+}\), iron has an oxidation state of +3.
- In \(\text{SO}_3\), sulfur has an oxidation state of +6.

### Step 3: Calculate the change in oxidation states
- For sulfur:
- It changes from -2 in FeS to +6 in SO3.
- Change = \( +6 - (-2) = +8 \)

- For iron:
- It changes from +2 in FeS to +3 in Fe3+.
- Change = \( +3 - (+2) = +1 \)

### Step 4: Determine the total number of electrons transferred
- The total number of electrons transferred in the reaction:
- Sulfur contributes 8 electrons (from -2 to +6).
- Iron contributes 1 electron (from +2 to +3).

Thus, the total number of electrons involved in the reaction is:
\[ 8 + 1 = 9 \text{ electrons} \]

### Step 5: Calculate the equivalent weight
The formula for equivalent weight is given by:
\[ \text{Equivalent Weight} = \frac{\text{Molecular Weight}}{n} \]
where \( n \) is the number of electrons transferred.

Given that the molecular weight of FeS is \( M \), we can substitute:
\[ \text{Equivalent Weight of FeS} = \frac{M}{9} \]

### Final Answer
The equivalent weight of FeS for this change is:
\[ \text{Equivalent Weight} = \frac{M}{9} \]

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