A brown banana on the counter exhibits both physical and chemical changes. Here are examples of each:
Evidence of a Physical Change:
- Texture Change: The banana's texture becomes softer as it ripens and browns. This change is physical because it involves a change in the banana's state without altering its chemical composition.
Evidence of a Chemical Change:
- Browning Reaction: The browning of the banana is primarily due to a chemical reaction called enzymatic browning, where the enzyme polyphenol oxidase reacts with oxygen in the air, leading to the formation of brown pigments (melanins). This is a chemical change because new substances are formed during the reaction.
In summary, the softening of the banana represents a physical change, while the enzymatic browning represents a chemical change.