The mass of the solid product of the reaction is determined by weighing.
Explanation:
protons have a relative charge of +1, they are located in the nucleus and the carry a positive charge
the electrons are negatively charged and have a charge of -1 . They are found orbiting on the shells .the electrons have a negligible mass of 1 / 1840
the neutrons have no charge they are located in the nucleus of an atom .