Which number completes the balanced chemical equation showing the process of rusting? 4Fe + 3O2  ____Fe2O3 A. 1 B. 2 C. 4 D. 12

Step 1: Break Down the Problem

We have the unbalanced equation for the rusting process: $4 \text{Fe} + 3 \text{O}_2 \rightarrow \_\_\_ \text{Fe}_2\text{O}_3$ We need to find the coefficient that balances the equation.

Step 2: Relevant Concepts

In the reaction, iron (Fe) reacts with oxygen (O2) to form iron(III) oxide (Fe2O3). To balance this reaction, we'll need to ensure that the number of each type of atom is the same on both sides of the equation.

Step 3: Analysis and Detail

1. On the left side:

   • There are 4 Fe atoms from the 4Fe.
   • There are 3 O2 molecules, contributing $3 \times 2 = 6$ O atoms.

2. On the right side:

   • Each formula unit of Fe2O3 contains 2 Fe atoms and 3 O atoms.

3. We can balance the equation by determining how many Fe2O3 units we need to match the 4 Fe atoms from the left side:

   • To have 4 Fe atoms on the right, we need $\frac{4 \text{ Fe}}{2 \text{ Fe per } \text{Fe}_2\text{O}_3} = 2 \text{Fe}_2\text{O}_3$.

Step 4: Verify and Summarize

Now checking the oxidation states and counts:

• Using 2Fe2O3 gives us $2 \times 3 = 6$ O atoms, which matches the 6 O atoms from the left side (3O2).

Final Answer

The balanced equation is: $4 \text{Fe} + 3 \text{O}_2 \rightarrow 2 \text{Fe}_2\text{O}_3$

Thus, the correct answer is B. 2.