In a chemical change, a substance undergoes a chemical reaction and transforms into a new product. Water consists of one atom of oxygen and two atoms of hydrogen. When we boil water, it undergoes a phase transformation as it transforms from one phase to another ^[1-4].

Liquid water transforms into water vapor. This phenomenon occurs at 100 °C, the boiling point of water. During this process, water molecules are not chemically altered. In other words, the hydrogen atoms are still bonded to oxygen atoms. There are no new substances formed. The change is purely physical.

A physical change occurs when a substance undergoes a physical transformation that alters its physical properties. The phenomenon is reversible. It holds for water since water vapor reverses into liquid water through condensation. Therefore, boiling water is not a chemical change.