What distinguishes a physical change from a chemical change?

A physical change is characterized by the transformation of a substance without altering its chemical composition. In this context, the accurate understanding is that during a physical change, the processes involved—such as changes in state (like melting or freezing), shape, or size—do not lead to the creation of new substances; the original substance retains its chemical properties.

For instance, when ice melts to become water, it remains H2O whether it is solid or liquid. The substance is the same, but its physical state has changed.

This understanding sets physical changes apart from chemical changes, where new substances are indeed formed through chemical reactions, accompanied by alterations in properties and composition. Therefore, the key distinction lies in the fact that no new substances are created in physical changes, making this explanation accurate and central to understanding the differences between physical and chemical changes.