* No new substances are formed: When sugar dissolves in coffee, the sugar molecules are simply dispersing throughout the coffee. They don't change their chemical composition. You can still recover the sugar by evaporating the coffee.

* The change is reversible: By evaporating the coffee, you can get the sugar back in its original form. This is a key characteristic of a physical change.

A chemical change would involve the formation of new substances with different properties. For example, burning sugar would be a chemical change because it produces carbon dioxide and water, which are different substances from sugar.