What does the law of conservation of mass state?

The law of conservation of mass states that mass is neither created nor destroyed in a chemical reaction. This principle implies that during any chemical process, the total mass of the reactants must equal the total mass of the products. Therefore, if a chemical reaction occurs in a closed system, the sum of the masses of all substances involved remains constant before and after the reaction. This foundational concept is critical in chemistry, as it helps scientists account for all materials in reactions and ensures that equations are balanced, reflecting the permanence of matter in chemical transformations.