* Chemical Properties describe how a substance reacts with other substances, resulting in a change in its chemical composition.

* Physical Properties can be observed without changing the substance's chemical makeup (e.g., color, melting point, density).

When an acid reacts with a base, a chemical reaction occurs. The acid and base molecules rearrange, forming new molecules, including water. This change in composition is a defining characteristic of a chemical property.

Example:

* Hydrochloric acid (HCl) reacts with sodium hydroxide (NaOH) to form sodium chloride (NaCl) and water (H₂O).

* HCl (acid) + NaOH (base) → NaCl (salt) + H₂O (water)

This reaction demonstrates a chemical change because the original substances (HCl and NaOH) are transformed into entirely different substances (NaCl and H₂O).