Calculate the mass of iron which will be converted into its oxide (`Fe_3O_4`) by the action of 9g of steam on it. [At mass of Fe=56] `Fe+H_2​O→Fe_3O_4+4H_2` ​

Options

A. 21g
B. 42g
C. 47g
D. 27g

Explanation

To solve the problem of calculating the mass of iron that will be converted into its oxide (`Fe_3O_4`) by the action of 9g of steam, we can follow these steps:

### Step 1: Write the balanced chemical equation
The balanced chemical equation for the reaction between iron and steam is:
\[ 3 \text{Fe} + 4 \text{H}_2\text{O} \rightarrow \text{Fe}_3\text{O}_4 + 4 \text{H}_2 \]

### Step 2: Calculate the molar masses
- The molar mass of iron (Fe) is given as 56 g/mol.
- The molar mass of water (H₂O) is approximately 18 g/mol.

### Step 3: Determine the total mass of reactants
From the balanced equation, we can see that:
- 3 moles of Fe react with 4 moles of H₂O.

Calculating the mass of 3 moles of iron:
\[ \text{Mass of Fe} = 3 \times 56 = 168 \text{ g} \]

Calculating the mass of 4 moles of water:
\[ \text{Mass of H}_2\text{O} = 4 \times 18 = 72 \text{ g} \]

### Step 4: Establish the ratio of iron to steam
From the balanced equation, we see that 168 g of iron reacts with 72 g of steam. We can set up a ratio to find out how much iron reacts with 9 g of steam.

### Step 5: Set up the proportion
Using the ratio derived from the balanced equation:
\[ \frac{168 \text{ g Fe}}{72 \text{ g H}_2\text{O}} = \frac{x \text{ g Fe}}{9 \text{ g H}_2\text{O}} \]

### Step 6: Solve for x (mass of iron)
Cross-multiply to solve for x:
\[ 168 \times 9 = 72 \times x \]
\[ 1512 = 72x \]
\[ x = \frac{1512}{72} = 21 \text{ g} \]

### Conclusion
The mass of iron that will be converted into its oxide by the action of 9 g of steam is **21 g**.

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