To say that mass is conserved during a physical change means that the total mass of a substance remains the same before and after the change, even though its physical properties (such as shape, state, or appearance) may alter. No mass is lost, created, or destroyed in the process; the atoms or particles are simply rearranged or change their state (e.g., from solid to liquid or liquid to gas) without any change in the amount of matter present
. For example, if ice melts into water, the mass of the ice before melting is exactly equal to the mass of the water after melting because the same molecules are present, only their state has changed
. Similarly, if you cut a cake into pieces, the total mass of the pieces is the same as the mass of the whole cake before cutting
. This principle is a direct application of the Law of Conservation of Mass , which states that in any physical or chemical process, the total mass remains constant because matter cannot be created or destroyed under normal conditions
. In summary:
- Mass conservation means total mass stays constant during a physical change.
- Physical changes affect appearance or state but not the chemical composition or total mass.
- Atoms or molecules are neither gained nor lost; they only rearrange or change state.
- This principle is foundational in physics and chemistry and applies to closed systems where matter cannot enter or leave
Thus, mass conservation during a physical change reflects the unchanging quantity of matter despite changes in form or appearance.
