Answer
[tex]\begin{gathered} 4Fe+3O_2\rightarrow2Fe_2O_3 \\ \text{The chemical equation is classified as a combination }reaction \end{gathered}[/tex]Explanation
Step 1: Tally the number of atoms based on subscript.
[tex]\begin{gathered} Fe+O_2\rightarrow Fe_2O_3 \\ Left\text{ side: Fe = 1, O = 2} \\ \text{Right side: Fe = 2, O = 3} \end{gathered}[/tex]Step 2: Start balancing the simple molecules first, in this case, the O₂
[tex]\begin{gathered} Fe+3O_2\rightarrow Fe_2O_3 \\ Left\text{ side: Fe = 1, O = 2}\times3=6 \\ \text{Right side: Fe = 2, O = 3} \end{gathered}[/tex]Note that there are now 6 O atoms on the left, and there must also be 6 O atoms on the right too. The right hand is one big molecule so whatever coefficient use to balance the O atoms would also apply to the bonded Fe atom.
[tex]\begin{gathered} Fe+3O_2\rightarrow2Fe_2O_3 \\ Left\text{ side: Fe = 1, O = 2}\times3=6 \\ \text{Right side: Fe = 2}\times2=4\text{, O = 3}\times2=6 \end{gathered}[/tex]Step 3: Finally balance the rest of the equation.
[tex]\begin{gathered} 4Fe+3O_2\rightarrow2Fe_2O_3 \\ Left\text{ side: Fe = 1}\times4=4\text{, O = 2}\times3=6 \\ \text{Right side: Fe = 2}\times2=4\text{, O = 3}\times2=6 \end{gathered}[/tex]The equation is now balanced.
The chemical equation is classified as a combination reaction
