Which changes to matter are described by the law of conservation of mass?

1 answer

The law of conservation of mass states that mass in a closed system remains constant, regardless of the processes happening within that system. In other words, matter can change forms—such as during chemical reactions (where reactants are transformed into products)—but the total mass before the reaction must equal the total mass after the reaction.

Here are some key points related to changes to matter as described by the law of conservation of mass:

  1. Chemical Reactions: In chemical reactions, atoms are rearranged to form new substances, but no atoms are created or destroyed. Therefore, the mass of reactants equals the mass of products.

  2. Physical Changes: During physical changes (like melting, freezing, or evaporating), the form of matter changes, but the mass remains the same. For example, when ice melts to water, its mass does not change.

  3. State Changes: When matter changes states (solid, liquid, gas), the total mass remains constant. For instance, boiling water transforms into steam, but the total mass of the water and steam is equal.

  4. Closed Systems: The law applies specifically to closed systems, where no matter enters or leaves. In an open system, mass may appear to change because of exchanged matter with the surroundings.

In summary, according to the law of conservation of mass, even though matter may undergo various physical or chemical changes, the total mass of the substances involved remains unchanged.