Science
Conservation of mass.
Definition
The law of conservation of mass states that matter cannot be created or destroyed in a chemical reaction. The total mass of reactants must equal the total mass of products, which is why chemical equations must be balanced.
Examples
Real-world.
- 1 When wood burns, the mass of ash plus gases produced equals the mass of wood plus oxygen consumed
- 2 In the reaction 2H₂ + O₂ → 2H₂O, 4 g of hydrogen plus 32 g of oxygen yields exactly 36 g of water
- 3 Antoine Lavoisier demonstrated this law by carefully weighing reactants and products in sealed containers
Key Fact
Mass of reactants = Mass of products in every chemical reaction.