Chemical equations are fundamental tools in chemistry that represent chemical reactions. They exemplify the conservation of mass, which is a principle stating that matter cannot be created or destroyed in a closed system. This means that the total mass of the reactants (the starting materials) must equal the total mass of the products (the substances formed). When we write a chemical equation, we ensure that the number of atoms for each element is the same on both sides of the equation.
For instance, consider the combustion of methane (CH₄):
Reactants: CH₄ + 2 O₂
Products: CO₂ + 2 H₂O
In this equation, one carbon atom, four hydrogen atoms, and four oxygen atoms are present on the reactant side. On the product side, you also have one carbon atom, four hydrogen atoms (in two water molecules), and four oxygen atoms (in one carbon dioxide molecule and two water molecules). Thus, the total number of each type of atom remains constant, illustrating that mass is conserved.
Moreover, balancing the equation ensures that all atoms are accounted for, further supporting the conservation of mass. This fundamental concept is crucial for understanding how chemical reactions occur and is foundational in chemical science.