Atoms in Chemical Reactions: Mastery Test

Iron reacts with oxygen to produce iron oxide (rust). This reaction is represented in an equation as [tex]4 \, \text{Fe} + x \, \text{O}_2 \rightarrow 2 \, \text{Fe}_2\text{O}_3[/tex]. Identify the value of [tex]x[/tex] that will balance the equation.



Answer :

To balance the chemical equation for the reaction of iron with oxygen to produce iron oxide, we follow these steps:

1. Write the given chemical equation:
[tex]\[ 4 Fe + x O_2 \rightarrow 2 Fe_2O_3 \][/tex]

2. Determine the number of each type of atom on both sides of the equation:
- On the left side of the equation:
- Fe atoms: 4
- O atoms: [tex]\(2 \times x\)[/tex] (since [tex]\(O_2\)[/tex] has 2 oxygen atoms per molecule)

- On the right side of the equation:
- Fe atoms: [tex]\(2 \times 2 = 4\)[/tex] (since [tex]\(Fe_2O_3\)[/tex] has 2 iron atoms per molecule and we have 2 molecules)
- O atoms: [tex]\(3 \times 2 = 6\)[/tex] (since [tex]\(Fe_2O_3\)[/tex] has 3 oxygen atoms per molecule and we have 2 molecules)

3. Set up the equality for the oxygen atoms to ensure the equation is balanced:
- The number of oxygen atoms on the left side should be equal to the number of oxygen atoms on the right side. Thus, we get:
[tex]\[ 2x = 6 \][/tex]

4. Solve for [tex]\(x\)[/tex]:
- Divide both sides of the equation by 2:
[tex]\[ x = \frac{6}{2} \][/tex]
[tex]\[ x = 3 \][/tex]

5. Conclusion:
The value of [tex]\(x\)[/tex] that balances the equation is:
[tex]\[ x = 3 \][/tex]

Thus, the balanced chemical equation is:
[tex]\[ 4 Fe + 3 O_2 \rightarrow 2 Fe_2O_3 \][/tex]