Yes, chemical equations do obey the law of conservation of mass. This fundamental principle states that in a closed system, the mass of the reactants must equal the mass of the products. Essentially, this means that during a chemical reaction, matter is neither created nor destroyed.
When we write a chemical equation, we represent the reactants on the left side and the products on the right side. For the equation to accurately depict the reaction, the number of atoms of each element must be the same on both sides of the equation. This ensures that mass is conserved throughout the reaction.
For example, consider the combustion of methane:
CH4 + 2 O2 → CO2 + 2 H2O
In this reaction, one molecule of methane reacts with two molecules of oxygen to produce one molecule of carbon dioxide and two molecules of water. Counting the atoms, we have:
- Reactants: 1 carbon (C) + 4 hydrogen (H) + 4 oxygen (O) = 9 atoms
- Products: 1 carbon (C) + 4 hydrogen (H) + 4 oxygen (O) = 9 atoms
As we can see, the number of each type of atom is balanced on both sides, which demonstrates that the reaction conserves mass. Therefore, chemical equations are formulated in such a way that they reflect this principle, aligning perfectly with the law of conservation of mass.