Chemical reactions are crucial in understanding the behavior of matter in our universe. One example of such a reaction is an oxidation-reduction (redox) reaction. In the following reaction, iron(II) chloride (FeCl2) acts as a reducing agent, while oxygen (O2) acts as an oxidizing agent:

*4 FeII - 4 e- → 4 FeIII (oxidation)*

*2 O0 + 4 e- → 2 O-II (reduction)*

## Word equation

*Iron(II) chloride + oxygen + water → Iron(III) oxide + Hydrogen chloride*

This can be represented algebraically by the following unbalanced chemical equation:

*4 FeCl2 + 3 O2 + 6 H2O → 2 Fe2O3 + 8 HCl*

To balance this equation, we need to add stoichiometric coefficients to the reactants and products. The coefficients should be chosen in a way that the number of atoms in the reactants equals the number of atoms in the products for all elements present. We can represent these coefficients as c1, c2, c3, c4, and c5, respectively.

After equating the number of atoms for Cl, Fe, O, and H, we can solve the system of equations to obtain the coefficients. To keep the coefficients small, we can set an arbitrary value for one of them. In this case, we set c2 = 1 and obtain the following coefficients:

*c1 = 4, c2 = 1, c3 = 4, c4 = 2, c5 = 8*

Substituting these coefficients into the chemical equation gives us the balanced equation:

*4 FeCl2 + 3 O2 + 6 H2O → 2 Fe2O3 + 8 HCl*

This balanced equation represents the same chemical reaction as the word equation above.

Understanding chemical reactions and being able to balance chemical equations is important not only for scientists but also for students and professionals in various fields.