Answer:
The law of conservation of mass
Step-by-step explanation:
A chemical equation is an expression of the net composition change associated with a chemical reaction. It shows how a certain amount of reactants yields a certain amount of products. Both of these amounts are measured in moles. Chemical equations often contain information about the state of the reactants: solid, liquid, gas, or aqueous. In addition, they always adhere to the law of conservation of mass, which holds that matter can change form, but cannot be created or destroyed.