To balance the chemical equation for the reaction of iron with atmospheric oxygen to form iron(III) oxide (ferric oxide), let us start with the unbalanced equation provided:
[tex]\[ \text{Fe} + \text{O}_2 \rightarrow \text{Fe}_2\text{O}_3 \][/tex]
### Step-by-Step Balancing
#### Step 1: Count the Number of Atoms of Each Element
First, we'll count the number of iron (Fe) and oxygen (O) atoms on both sides of the unbalanced equation.
- Reactants:
- Iron (Fe) atoms: 1
- Oxygen (O) atoms: 2
- Products:
- Iron (Fe) atoms: 2
- Oxygen (O) atoms: 3
#### Step 2: Balance Iron (Fe) Atoms
To balance the number of Fe atoms on both sides, we need to have the same number of Fe atoms in the reactants and in the products. Since Fe appears as a single atom on the reactant side and as part of \(\text{Fe}_2\text{O}_3\) on the product side, we can place a coefficient of 4 in front of Fe on the reactant side, giving us:
[tex]\[ 4 \text{Fe} + \text{O}_2 \rightarrow 2 \text{Fe}_2\text{O}_3 \][/tex]
- Reactants:
- Iron (Fe) atoms: 4
- Oxygen (O) atoms: 2
- Products:
- Iron (Fe) atoms: 4 (since there are 2 \(\text{Fe}_2\text{O}_3\) molecules, and each contains 2 Fe atoms)
- Oxygen (O) atoms: 6 (since there are 2 \(\text{Fe}_2\text{O}_3\) molecules, and each contains 3 O atoms)
#### Step 3: Balance Oxygen (O) Atoms
To balance the number of O atoms, we now see that we have 2 O atoms on the reactant side and 6 O atoms on the product side. To balance this, we need to place a coefficient of 3 in front of \(\text{O}_2\) on the reactant side, giving us:
[tex]\[ 4 \text{Fe} + 3 \text{O}_2 \rightarrow 2 \text{Fe}_2\text{O}_3 \][/tex]
- Reactants:
- Iron (Fe) atoms: 4
- Oxygen (O) atoms: 6 (since there are 3 \(\text{O}_2\) molecules, and each contains 2 O atoms)
- Products:
- Iron (Fe) atoms: 4
- Oxygen (O) atoms: 6
Now the equation is balanced, with 4 Fe atoms and 6 O atoms on both the reactant and product sides.
### Conclusion
The balanced chemical equation for the reaction of iron with oxygen to form iron(III) oxide is:
[tex]\[ 4 \text{Fe} + 3 \text{O}_2 \rightarrow 2 \text{Fe}_2\text{O}_3 \][/tex]
Thus, the correct answer is:
A. [tex]\( 4 \text{Fe} + 3 \text{O}_2 \rightarrow 2 \text{Fe}_2\text{O}_3 \)[/tex]
