Question

physical and chemical properties and changes
name zach
physical property

1. observed with senses
2. determined without destroying matter

chemical property

1. indicates how a substance reacts with something else
2. matter will be changed into a new substance after the reaction

identify the following as a chemical (c) or physical property (p):

1. blue color
2. density
3. flammability (burns)
4. solubility (dissolves)
5. reacts with acid
6. supports combustion
7. sour taste
8. melting point
9. reacts with water
10. hardness
11. boiling point
12. luster
13. odor
14. reacts with air

physical change

1. a change in size, shape, or state
2. no new substance is formed

chemical change

1. a change in the physical and chemical properties
2. a new substance is formed

identify the following as physical (p) or chemical (c) changes.

1. nacl (table salt) dissolves in water.
2. ag (silver) tarnishes.
3. an apple is cut.
4. heat changes h₂o to steam.
5. baking soda reacts to vinegar.
6. fe (iron) rusts.
7. alcohol evaporates.
8. ice melts.
9. milk sours.
10. sugar dissolves in water.
11. wood rots.
12. pancakes cook.
13. grass grows.
14. a tire is inflated.
15. food is digested.
16. paper towel absorbs water.

physical and chemical changes
part a
can you recognize the chemical and physical changes that happen all around us? if you change the way something looks, but haven’t made a new substance, a physical change (p) has occurred. if the substance has been changed 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.
2. two chemicals are mixed together and a gas is produce.
3. a bicycle changes color as it rusts.
4. a solid is crashed to a powder.
5. two substances are mixed and light is produced.
6. a piece of ice melts and reacts with sodium.
7. mixing salt and pepper.
8. chocolate syrup is dissolved in milk.
9. a marshmallow is toasted over a campfire.
10. a marshmallow is cut in half.

Explanation:

Step1: Recall physical and chemical property definitions

Physical properties are observed with senses and determined without destroying matter. Chemical properties indicate how a substance reacts and result in a new - substance formation.

Step2: Analyze each property

1. Blue color: Observed with eyes, no new - substance formation. Physical (P).
2. Density: Measured without changing the substance chemically. Physical (P).
3. Flammability: Substance reacts and burns to form new substances. Chemical (C).
4. Solubility: Substance dissolves, no new - substance formation. Physical (P).
5. Reacts with acid: Forms new substances. Chemical (C).
6. Supports combustion: Chemical reaction occurs. Chemical (C).
7. Sour taste: Observed with taste, no chemical reaction for just tasting. Physical (P).
8. Melting point: Change in state, no new - substance formation. Physical (P).
9. Reacts with water: Forms new substances. Chemical (C).
10. Hardness: Observed without chemical change. Physical (P).
11. Boiling point: Change in state, no new - substance formation. Physical (P).
12. Luster: Observed with eyes, no chemical change. Physical (P).
13. Odor: Observed with smell, no chemical change. Physical (P).
14. Reacts with air: Forms new substances. Chemical (C).

Step3: Recall physical and chemical change definitions

Physical change is a change in size, shape, or state with no new - substance formation. Chemical change results in new - substance formation.

Step4: Analyze each change

1. NaCl dissolves in water: No new - substance formation. Physical (P).
2. Ag tarnishes: Forms new substances (silver sulfide). Chemical (C).
3. An apple is cut: Change in shape, no new - substance. Physical (P).
4. Heat changes H₂O to steam: Change in state, no new - substance. Physical (P).
5. Baking soda reacts to vinegar: Forms new substances (carbon dioxide etc.). Chemical (C).
6. Fe rusts: Forms new substances (iron oxide). Chemical (C).
7. Alcohol evaporates: Change in state, no new - substance. Physical (P).
8. Ice melts: Change in state, no new - substance. Physical (P).
9. Milk sours: Forms new substances (lactic acid etc.). Chemical (C).
10. Sugar dissolves in water: No new - substance formation. Physical (P).
11. Wood rots: Forms new substances through decomposition. Chemical (C).
12. Pancakes cook: Chemical reactions occur (e.g., Maillard reaction). Chemical (C).
13. Grass grows: Chemical reactions in photosynthesis etc. Chemical (C).
14. A tire is inflated: Change in shape, no new - substance. Physical (P).
15. Food is digested: Chemical reactions break down food. Chemical (C).
16. Paper towel absorbs water: No new - substance formation. Physical (P).

Step5: Analyze Part A changes

1. An ice cube is placed in the sun and melts: Change in state, no new - substance. Physical (P).
2. Two chemicals are mixed and a gas is produced: New - substance formation. Chemical (C).
3. A bicycle changes color as it rusts: Forms new substances (iron oxide). Chemical (C).
4. A solid is crushed to a powder: Change in shape, no new - substance. Physical (P).
5. Two substances are mixed and light is produced: Chemical reaction occurs. Chemical (C).
6. A piece of ice melts and reacts with sodium: Melting is physical, reaction with sodium is chemical. Chemical (C).
7. Mixing salt and pepper: No new - substance formation. Physical (P).
8. Chocolate syrup is dissolved in milk: No new - substance formation. Physical (P).
9. A marshmallow is toasted over a campfire: Chemical reactions occur (carbonization etc.). Chemical (C).
10. A marshmallow is cut in half: Change in shape, no new - substance. Physical (P).

Answer:

1. P
2. P
3. C
4. P
5. C
6. C
7. P
8. P
9. C
10. P
11. P
12. P
13. P
14. C
15. P
16. C
17. P
18. P
19. C
20. C
21. P
22. P
23. C
24. P
25. C
26. C
27. C
28. P
29. C
30. P
31. P
32. C
33. C
34. P
35. C
36. C
37. P
38. P
39. C
40. P