Fe + O2 → Fe2O3 This equation is unbalanced. Which of the following is the correct balanced equation for this reaction? A. 4Fe + 3O2 → 2Fe2O3 B. 3Fe + 4O2 → 2Fe2O3 C. 2Fe + 4O2 → 3Fe2O3 D. 3Fe + 3O2 → 4Fe2O3 E. 4Fe + 4O2 → 3Fe2O3
The Correct Answer and Explanation is:
The correct answer is: A. 4Fe + 3O₂ → 2Fe₂O₃
Explanation
To balance a chemical equation, we must ensure that the number of atoms of each element is the same on both sides of the equation. In this reaction, iron (Fe) reacts with oxygen (O₂) to form iron(III) oxide (Fe₂O₃). Here’s how we balance it step-by-step:
Step 1: Write the Unbalanced Equation
The unbalanced equation for the reaction is:
[
\text{Fe} + \text{O}_2 \rightarrow \text{Fe}_2\text{O}_3
]
Step 2: Balance the Iron (Fe) Atoms
In the compound Fe₂O₃, there are 2 atoms of Fe. To balance the Fe atoms, we need 2 Fe atoms on the reactant side:
[
2\text{Fe} + \text{O}_2 \rightarrow \text{Fe}_2\text{O}_3
]
This equation is still unbalanced because the oxygen atoms do not match on both sides.
Step 3: Balance the Oxygen (O) Atoms
In Fe₂O₃, there are 3 oxygen atoms. However, on the reactant side, oxygen is in the form of O₂ molecules, so we have pairs of oxygen atoms. To balance the oxygen, we need to make the total number of oxygen atoms on both sides equal.
Since each O₂ molecule has 2 oxygen atoms, we can use 3 O₂ molecules to get a total of 6 oxygen atoms:
[
2\text{Fe} + 3\text{O}_2 \rightarrow \text{Fe}_2\text{O}_3
]
Now, we have balanced the oxygen, but we need more iron atoms on the reactant side.
Step 4: Adjust Iron Atoms to Match
To balance the iron atoms, we need a total of 4 Fe atoms on the reactant side to match 2 molecules of Fe₂O₃:
[
4\text{Fe} + 3\text{O}_2 \rightarrow 2\text{Fe}_2\text{O}_3
]
Final Balanced Equation
Now, we have 4 Fe atoms and 6 O atoms on both sides. This makes the equation:
[
4\text{Fe} + 3\text{O}_2 \rightarrow 2\text{Fe}_2\text{O}_3
]
This is the balanced equation, confirming that option A is correct. Balancing chemical equations is essential to reflect the conservation of mass, ensuring that atoms are neither created nor destroyed in chemical reactions.