Select the correct answer.

Iron reacts with atmospheric oxygen to form iron oxide or ferric oxide. Look at the chemical equation for this reaction:

[tex]\[ Fe + O_2 \rightarrow Fe_2O_3 \][/tex]

This equation is unbalanced. Which of the following is the correct balanced equation for this reaction?

A. [tex]\[ 4Fe + 3O_2 \rightarrow 2Fe_2O_3 \][/tex]

B. [tex]\[ 3Fe + 4O_2 \rightarrow 2Fe_2O_3 \][/tex]

C. [tex]\[ 2Fe + 4O_2 \rightarrow 3Fe_2O_3 \][/tex]

D. [tex]\[ 3Fe + 3O_2 \rightarrow 4Fe_2O_3 \][/tex]

E. [tex]\[ 4Fe + 4O_2 \rightarrow 3Fe_2O_3 \][/tex]



Answer :

To balance the chemical equation for the reaction of iron with oxygen to form iron oxide ([tex]\(Fe_2O_3\)[/tex]), follow these steps:

1. Write the unbalanced equation:
[tex]\[ Fe + O_2 \rightarrow Fe_2O_3 \][/tex]

2. List the number of atoms of each element on both sides of the equation:
- Left side: 1 Fe, 2 O
- Right side: 2 Fe, 3 O

3. Balance the iron (Fe) atoms:
- On the right side, there are 2 Fe atoms.
- To balance Fe on the left side, place a coefficient of 2 in front of Fe:
[tex]\[ 2 Fe + O_2 \rightarrow Fe_2O_3 \][/tex]
- Now the count is:
- Left side: 2 Fe, 2 O
- Right side: 2 Fe, 3 O

4. Balance the oxygen (O) atoms:
- On the right side, there are 3 O atoms.
- On the left side, each [tex]\(O_2\)[/tex] molecule contains 2 O atoms. To balance the oxygen atoms, place a coefficient of 3/2 in front of [tex]\(O_2\)[/tex]:
[tex]\[ 2 Fe + \frac{3}{2} O_2 \rightarrow Fe_2O_3 \][/tex]
- Now the count is:
- Left side: 2 Fe, [tex]\(3 \times \frac{1}{2} = 3\)[/tex] O
- Right side: 2 Fe, 3 O

5. To avoid fractional coefficients, multiply the entire equation by 2 to get whole numbers:
[tex]\[ 4 Fe + 3 O_2 \rightarrow 2 Fe_2O_3 \][/tex]

6. Re-check the balance:
- Left side: 4 Fe, 6 O
- Right side: 4 Fe, 6 O

The equation is now balanced.

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

Comparing this to the given options:
- Option A: [tex]\(4 Fe +3 O_2 \rightarrow 2 Fe_2O_3\)[/tex]

The correct answer is:
A. [tex]\(4 Fe +3 O_2 \rightarrow 2 Fe_2O_3\)[/tex]