Calculate the mass of iron which will be converted into its oxide (`Fe_3O_4`) by the action of 21g of steam on it. [At mass of Fe=56] `Fe+H_2​O→Fe_3O_4+4H_2` ​

Explanation

To calculate the mass of iron that will be converted into its oxide (Fe₃O₄) by the action of 21g of steam, we can follow these steps:

### Step 1: Write the balanced chemical equation
The reaction of iron with steam is given by the equation:
\[ \text{Fe} + \text{H}_2\text{O} \rightarrow \text{Fe}_3\text{O}_4 + 4\text{H}_2 \]

### Step 2: Balance the equation
The balanced equation can be written as:
\[ 3\text{Fe} + 4\text{H}_2\text{O} \rightarrow \text{Fe}_3\text{O}_4 + 4\text{H}_2 \]

### Step 3: Calculate the molar mass of Fe and H₂O
- The molar mass of iron (Fe) is given as 56 g/mol.
- The molar mass of water (H₂O) can be calculated as:
\[ \text{H}_2\text{O} = 2 \times 1 + 16 = 18 \text{ g/mol} \]

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

Calculating the total mass of iron and water:
- Mass of 3 moles of Fe:
\[ 3 \times 56 = 168 \text{ g} \]
- Mass of 4 moles of H₂O:
\[ 4 \times 18 = 72 \text{ g} \]

### Step 5: Set up a proportion to find the mass of iron for 21g of steam
We know that 72g of steam reacts with 168g of iron. We need to find out how much iron reacts with 21g of steam.

Using the proportion:
\[ \frac{168 \text{ g Fe}}{72 \text{ g H}_2\text{O}} = \frac{x \text{ g Fe}}{21 \text{ g H}_2\text{O}} \]

### Step 6: Solve for x (mass of iron)
Cross-multiplying gives:
\[ 168 \times 21 = 72 \times x \]
\[ 3528 = 72x \]
\[ x = \frac{3528}{72} = 49 \text{ g} \]

### Final Answer
The mass of iron that will be converted into its oxide by the action of 21g of steam is **49 grams**.

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