if gases are released by a chemical reaction then the total mass of the product will be less than the total mass of the reactants
combustion_reaction is chemical_reaction. developing_chemical_weapons is developing_product. condensation_reaction is chemical_reaction. reactant is chemical. product is chemical. periodic_acid is chemical_compound. propionic_acid is chemical_compound. chemical_reaction is chemical_process. acid is chemical. propionate is chemical_compound.