Conservation of mass — Science definition
Matter remains accounted for when the complete relevant system and exchanges are included.
Where it is taught
- Chemical Changes: Evidence & Conservation — Matter, Mixtures & Water Properties, Science 6: Matter, Energy & Earth Systems, Grade 6
Questions using conservation of mass
Problem 1
Which statement correctly uses conservation of mass in Chemical Changes: Evidence & Conservation?
- conservation of mass: Matter remains accounted for when the complete relevant system and exchanges are included.
- Any bubbles or color change conclusively prove a chemical reaction.
- A mass change inside an open container means matter was destroyed.
- One illustrative result establishes every real condition and needs no further evidence.
Answer and explanation
conservation of mass: Matter remains accounted for when the complete relevant system and exchanges are included.
Matter remains accounted for when the complete relevant system and exchanges are included. Two A atoms and two B atoms are represented on each side. Their combinations change from A₂ and B₂ to two AB particles. The closed-system mass remains 60 g. This model directly states a rearrangement; a color change alone would not supply the same evidence of substance identity.