Balance this equation:
Fe(s) + O2(g) ? Fe2O3(s)
Express your answer as a chemical equation. Identify all of the phases in your answer.
The Correct Answer and Explanation is:
Balanced Chemical Equation: 4Fe(s)+3O2(g)→2Fe2O3(s)4Fe(s) + 3O_2(g) \rightarrow 2Fe_2O_3(s)
Explanation
Balancing chemical equations is essential for reflecting the Law of Conservation of Mass, which states that matter cannot be created or destroyed in a chemical reaction. This means the number of atoms of each element must be the same on both sides of the equation.
In the given reaction: Fe(s)+O2(g)→Fe2O3(s)\text{Fe(s)} + \text{O}_2\text{(g)} \rightarrow \text{Fe}_2\text{O}_3\text{(s)}
we are reacting elemental iron (Fe, a solid) with diatomic oxygen gas (O₂, a gas) to produce iron(III) oxide (Fe₂O₃, a solid).
Step-by-step balancing:
- Write the unbalanced formula: Fe(s)+O2(g)→Fe2O3(s)\text{Fe}(s) + \text{O}_2(g) \rightarrow \text{Fe}_2O_3(s)
- Balance Fe atoms:
On the right side, Fe₂O₃ contains 2 iron atoms. So we need 4 iron atoms on the left to make two formula units of Fe₂O₃: 4Fe(s)+O2(g)→2Fe2O3(s)4Fe(s) + O_2(g) \rightarrow 2Fe_2O_3(s) - Balance O atoms:
The product side now has 2 × 3 = 6 oxygen atoms (because 2 Fe₂O₃ units each contain 3 O atoms). So, to get 6 oxygen atoms from O₂ molecules, we need 3 O₂ molecules: 4Fe(s)+3O2(g)→2Fe2O3(s)4Fe(s) + 3O_2(g) \rightarrow 2Fe_2O_3(s)
Now, both sides have:
- 4 iron (Fe) atoms
- 6 oxygen (O) atoms
Phases:
- Fe(s): solid iron
- O₂(g): oxygen gas
- Fe₂O₃(s): solid iron(III) oxide
This balanced equation accurately represents the synthesis of iron(III) oxide (rust) from iron and oxygen, a common reaction seen in corrosion processes.
