Question

How would you balance the following equation: $\mathrm{Fe}+{\mathrm{O}}_2\to {\mathrm{Fe}}_2{\mathrm{O}}_3$

Answer 1

Balancing the Chemical equation:

• When we balance chemical equations, we want the same number of each sort of atom on both sides of the equation.
• Only the coefficients are changed. The numbers in front of the molecule are called coefficients.
• Subscripts should never be changed.
• Metals must be balanced first, followed by nonmetals such as oxygen and hydrogen.
• The unbalanced chemical reaction provided is

$\underset{\mathrm{Iron}}{\mathrm{Fe}\left(\mathrm{s}\right)}+\underset{\mathrm{Oxygen}}{{\mathrm{O}}_2\left(\mathrm{g}\right)}\to \underset{\mathrm{Ferric}\mathrm{oxide}}{{\mathrm{Fe}}_2{\mathrm{O}}_3\left(\mathrm{s}\right)}$

• It is a redox synthesis that leads to the formation of Ferric Oxide, as shown in the reaction.

Reactant side	Product side
1 Iron atom from $\mathrm{Fe}$	2 Iron atoms from ${\mathrm{Fe}}_2{\mathrm{O}}_3$
2 Oxygen atoms from ${\mathrm{O}}_2$	3 Oxygen atoms from ${\mathrm{Fe}}_2{\mathrm{O}}_3$

• As we can see, there are $3$ Oxygen atoms on the right, and two Oxygen atoms on the left. So, we must put $3$ on the left side and $2$on the product side as shown below:

$\underset{\mathrm{Iron}}{\mathrm{Fe}\left(\mathrm{s}\right)}+\underset{\mathrm{Oxygen}}{3{\mathrm{O}}_2\left(\mathrm{g}\right)}\to \underset{\mathrm{Ferric}\mathrm{oxide}}{2{\mathrm{Fe}}_2{\mathrm{O}}_3\left(\mathrm{s}\right)}$

Reactant side	Product side
1 Iron atom from $\mathrm{Fe}$	4 Iron atoms from ${\mathrm{Fe}}_2{\mathrm{O}}_3$
6 Oxygen atoms from ${\mathrm{O}}_2$	6 Oxygen atoms from ${\mathrm{Fe}}_2{\mathrm{O}}_3$

• Second, the Iron must be balanced. As shown on the left, there is one Iron atom, and four Iron atoms on the product side; thus, a $4$ must be inserted on the right side before Iron metal to balance.

$\underset{\mathrm{Iron}}{4\mathrm{Fe}\left(\mathrm{s}\right)}+\underset{\mathrm{Oxygen}}{3{\mathrm{O}}_2\left(\mathrm{g}\right)}\to \underset{\mathrm{Ferric}\mathrm{oxide}}{2{\mathrm{Fe}}_2{\mathrm{O}}_3\left(\mathrm{s}\right)}$

Reactant side	Product side
4 Iron atoms from $\mathrm{Fe}$	4 Iron atoms from ${\mathrm{Fe}}_2{\mathrm{O}}_3$
6 Oxygen atoms from ${\mathrm{O}}_2$	6 Oxygen atoms from ${\mathrm{Fe}}_2{\mathrm{O}}_3$

• Thus, the balanced chemical reaction is:

$\underset{\mathrm{Iron}}{4\mathrm{Fe}\left(\mathrm{s}\right)}+\underset{\mathrm{Oxygen}}{3{\mathrm{O}}_2\left(\mathrm{g}\right)}\to \underset{\mathrm{Ferric}\mathrm{oxide}}{2{\mathrm{Fe}}_2{\mathrm{O}}_3\left(\mathrm{s}\right)}$