What does the law of conservation of mass state?

The law of conservation of mass states that in any chemical reaction, the total mass of the reactants must equal the total mass of the products. This principle implies that mass is not created or destroyed during the reaction, but instead, it is rearranged. When substances undergo a chemical change, the atoms involved are simply reorganized into new compounds, while the total number of atoms—and thus the total mass—remains constant throughout the process.

This foundational principle is crucial in understanding chemical reactions, stoichiometry, and the balance of chemical equations, as it ensures that the mass before the reaction is the same as the mass after the reaction, reinforcing the idea that mass is conserved in any closed system.