Is the weight change in a chemical change?

Answer 1

NOTHING. Mass will never change in a chemical reaction, the total mass of the products is ALWAYS equal to the total mass of the reactants. In many reactions however, their seems to be an apparent change in mass, and that is because some of the products may have been pulled out of the air, or perhaps some of the reactants are gasses and have risen into the atmosphere. The one time a change in mass is real is in a nuclear reaction, but they are not chemical reactions and thus will be ignored in answering this question. Chemical reactions never change the nucleus in anyway, they only change the way electrons are configurated.

Answer 2

Weight is the force acting on a massive body inserted into a gravitational field (generally the gravitation on the earth surface is considered, so that weight is the weight on earth surface).

Being a force, weight has a relevance in all physical phenomena implying body motion. Sometimes chemical reactions happens while the involved species are in motion while in solution (like in a dynamic chemical reactor or in a microfluidics chip): in this case weight can be an important parameter also to design chemical systems.

Weight is also used in the sense of "Molecular weight". In this case however, the world weight is not rigorous, since the "Molecular weight" should be called molecular mass, since it measures the mass of a given molecule (or of a mole of such substance, that is a number of molecules equal to the Avogadro number).

Being the "molecular weight" in reality the measure of a mass, it is completely independent from the gravitational field and it is one of the main variables in chemical problems.

Answer 3

Yes, in a chemical change the total weight of the substances involved remains constant according to the law of conservation of mass.

Answer 4

yes