- Solid moth balls gradually vaporize in a closet: Physical, Change, The moth balls change from solid to gas without altering their chemical composition.
- Hydrofluoric acid attacks glass and is used to etch calibration marks on glass laboratory utensils: Chemical, Change, HF reacts with silica in glass to form new compounds, changing the material chemically.
- A French chef making a sauce with Brandy is able to boil off the alcohol from the brandy, leaving just the brandy flavor: Physical, Change, Alcohol evaporates due to its lower boiling point; no new substances are formed.
- Chemistry majors sometimes get holes in the cotton jeans they wear to lab because of acid spills: Chemical, Change, Acid reacts with cellulose in cotton, breaking down the fabric chemically.
- The cutting of food: Physical, Change, Food is divided into smaller pieces without any change in chemical identity.
- In the iodine clock reaction two clear solutions are mixed together and turn a startling black color after a few minutes of mixing: Chemical, Change, A new substance (triiodide-starch complex) forms, causing the color change.
- A blue sports drink is mixed with a red berry juice to make a purple mixed drink: Physical, Change, The colors blend visually; no chemical reaction occurs between the components.
Parent Tip: Review the logic above to help your child master the concept of worksheet on chemical and physical properties and changes.
