One truly elegant hypothesis of physics is the "zero-energy universe" hypothesis. It proposes that the net sum of the energy in the universe perfectly equates to zero. According to the idea, if ...

As a practical exercise ... create gas in contained conditions to show the mass does not change. The conservation of mass could be discussed in relation to the combustion of hydrocarbons.

11. Verification of the law of conservation of mass in a chemical reaction. Assessment of Practical Skills in Science outlines the specific experiments and activities included in the practical ...