Law of Conservation of mass-mass can neither be created nor destroyed in a chemical reaction. The mass of the system must remain constant over time.
Law of Reciprocal proportion - If two different elements combine separately with the same weight of a third element, the ratio of the masses in which they do so are either the same or a simple multiple of the mass ratio in which they combine.
Law of Constant proportions - It states that a chemical compound always contains exactly the same proportion of elements by mass.
Law of Conservation of energy - Energy can neither be created nor be destroyed. The total energy of an isolated system remains constant.