What does the law of conservation of matter state?
Simply that mass is conserved in every chemical process.
What do I mean by
It means that if I start with 10 g of reactant, from all sources, at most I can get 10 g of product. The principle of conservation of mass has been observed in every chemical reaction EVER observed. The principle is consistent with the notion that matter is composed of elementary particles of definite mass, which in another context we would term atoms and molecules.
This principle is why teachers go to such effort and trouble teaching the principle of stoichiometry, and why teachers insist that chemical equations be balanced. If the equation is unbalanced, then we know that it does not reflect chemical reality, actual reality in fact.
Can you think of a physical process where mass is not conserved?
As a question, suppose I were to burn a mass of
In other words, energy can only be converted from one form to another but not destroyed. And no matter the type of conversion, the total amount of energy to a system is always equivalent.