Question

The law of conservation of mass states mass cannot be created or destroyed during a chemical reaction. If 40 g of calcium reacts with 71 g of chlorine, how many grams of calcium chloride are produced? _____ g

Answer 1

The reaction equation for this reaction is:
Ca + Cl₂ → CaCl₂
Therefore, calcium chloride is the only product so the mass of calcium chloride will be equivalent to the sum of the masses of the reactants.
Mass of calcium chloride = 40 + 71
Mass of calcium chloride = 111 grams

The law of conservation of mass holds for all chemical reactions.