What does the law of conservation of mass state?

The law of conservation of mass states that mass cannot be created or destroyed in a closed system during a chemical reaction. This principle means that the total mass of reactants before a reaction will equal the total mass of the products after the reaction has taken place. It highlights that when substances undergo changes, their mass remains constant, even though they may change form or combine with other substances. This fundamental concept is critical in understanding chemical reactions and is foundational in both chemistry and physics, ensuring that the equations governing reactions are balanced in terms of mass.