Question

part a can you recognize the chemical and physical changes that happen all around us? if you change the way something looks, but havent made a new substance, a physical change (p) has occurred. if the substance has been changes into another substance, a chemical change (c) has occurred. 1. an ice cube is placed in the sun. later there is a puddle of water. later still the puddle is gone. physical 2. two chemical are mixed together and a gas is produce. chemical 3. a bicycle changes color as it rusts. chemical 4. a solid is crushed to a powder. physical 5. two substances are mixed and light is produced. chemical 6. a piece of ice melts and reacts with sodium. chemical 7. mixing salt and pepper. physical 8. chocolate syrup is dissolved in milk. physical 9. a marshmallow is toasted over a campfire. chemical 10. a marshmallow is cut in half. physical

Explanation:

Step1: Recall physical and chemical change definitions

Physical change: no new - substance formed, change in state or appearance. Chemical change: new substance formed.

Step2: Analyze each scenario

1. Ice - cube melting in the sun: Ice turns to water, change of state, no new substance. Physical change (P).
2. Chemicals mixing to produce gas: New substance (gas) formed. Chemical change (C).
3. Bicycle rusting: Iron reacts with oxygen to form iron oxide (rust), new substance. Chemical change (C).
4. Solid crushed to powder: Change in form, no new substance. Physical change (P).
5. Two substances mixed with gas produced: New substance (gas) formed. Chemical change (C).
6. Ice reacting with sodium: Chemical reaction, new substances formed. Chemical change (C).
7. Mixing salt and pepper: Just a mixture, no chemical reaction, no new substance. Physical change (P).
8. Chocolate syrup dissolved in milk: Dissolution, no new substance. Physical change (P).
9. Toasting marshmallow over campfire: Chemical reactions due to heat, new substances formed. Chemical change (C).
10. Cutting marshmallow in half: Change in shape, no new substance. Physical change (P).

Answer:

1. P
2. C
3. C
4. P
5. C
6. C
7. P
8. P
9. C
10. P