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 chemical reaction. This fundamental principle, established by Antoine Lavoisier in the late 18th century, indicates that the total mass of reactants in a chemical reaction must equal the total mass of the products. This means that during any chemical transformation, the amount of matter remains constant, although it may change forms.

This law is essential in chemistry as it allows scientists to predict the outcomes of reactions quantitatively. In practical applications, such as stoichiometry, it provides a basis for calculating the amounts of substances consumed and produced in reactions. Understanding that mass is conserved is crucial for making accurate predictions about chemical behavior and for ensuring that chemical processes are efficient and balanced. This principle applies to both closed systems, where no matter enters or leaves, and to any chemical reaction occurring under normal conditions.