Question

What is the law of conservation of mass?

Answer 1

The law of conservation of mass states that mass can neither be created nor be destroyed in an chemical reaction.

This means that the mass of a product in a chemical reaction will be equal to the sum of the mass of the reactants.

Answer 2

The law of conservation of mass states that mass cannot be created or destroyed during a chemical reaction. (basically the mass of the reactants need to equal the mass of the products).

I hope this helps.

As a side note: The law of conservation of mass somewhat brakes down in nuclear reactions since some mass is sometimes converted to energy.