My evidence supports my claim because in all of the chemical reactions used as evidence, the molecules of the reactants interacted to form new substances. These reactants looked different than the products, but always contained the same mass. In a chemical reaction, the mass of the products will always be equal to the mass of the reactants. No mass is gained or lost because in a chemical reaction, the number of atoms and molecules stays the same. The particles are just rearranged, hence the mass in a chemical reaction must be conserved. In the chemical reaction in which the reactants are sodium bicarbonate and acetic acid, the products are sodium acetate, water, and carbon dioxide. The particles of the reactants are 3 carbon, 5 hydrogen, 5