Here’s a summary of the evidence of physical changes and chemical changes based on the examples you provided:
Evidence of a Physical Change
- A balloon is much smaller after letting the air out. - The balloon's size change is a physical change, as the air is simply being removed.
- There is a liquid substance in a pot after putting in a chunk of butter. - The melting of butter is a physical change; it changes from solid to liquid form but remains butter.
Evidence of a Chemical Change
- Ash is present after a bonfire. - The production of ash indicates a chemical change, as the wood has burned and transformed into different substances.
- There is a sour smelling liquid present in a cup of milk that was left on the counter for 3 days. - The souring of milk is a chemical change due to fermentation and the growth of bacteria.
- There is a loud sound after a firework explodes in the air. - The explosion of fireworks is a chemical change because it involves a reaction that produces gases and different compounds.
- There is a brown banana on the counter that was originally yellow. - The browning of a banana is a chemical change due to the enzymatic reaction and oxidation processes that occur as it ripens.
In summary, physical changes generally involve changes of state or size without altering the chemical composition, while chemical changes involve a transformation into different substances.