Final answer:
Physical and chemical changes both observe the law of conservation of mass as the total mass remains constant throughout the changes.
Step-by-step explanation:
Types of Changes and the Law of Conservation of Mass
Chemists classify changes into two categories: physical changes and chemical changes. Physical changes do not alter the identity of a substance, while chemical changes transform one substance into another. The law of conservation of mass states that matter is not created or destroyed in a chemical reaction, so the total mass before and after the reaction remains the same.
Types of Changes that Follow the Law of Conservation of Mass:
- Physical changes: These changes involve alterations in the physical properties of a substance. Examples include changes of state, such as melting, freezing, boiling, or condensing.
- Chemical changes: These changes result in the formation of new substances with different chemical properties. Examples include burning, rusting, and digestion.
In summary, both physical and chemical changes observe the law of conservation of mass, as the total mass remains constant throughout the changes.