* Physical changes alter the form or appearance of a substance but not its chemical composition. When you boil water, you are changing its state from liquid to gas (steam). The water molecules themselves are still H₂O.

* Chemical changes result in the formation of new substances with different chemical properties. While the hot water might help the tea leaves release their flavor compounds, the water itself doesn't undergo a chemical transformation.

Let me know if you'd like more examples of physical and chemical changes!