How does the law of conservation of mass relate to changes in physical state? how does it relate to chemical changes?

The Law of Conservation of Mass states that matter cannot be created nor destroyed. It can only be transformed from one state or substance to another. This means that this law applies to both physical and chemical changes. In physical changes, the substance before and after the phase change still has the same mass. In chemical changes, the mass of reactants will always have the same mass of products and by-products.