Question

new utrecht high school - regents chemistry
name
date
period

physical and chemical changes

part i - based on the demonstration of combining sodium polyacrylate with water. determine if it was a physical or chemical change and explain your reasoning using your observations and knowledge.

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

1. color
2. density
3. flammability
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

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

1. nacl
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, forming iron oxide (fe₂o₃)
7. alcohol evaporates
8. ice melts
9. milk sours
10. sugar dissolves in water
11. wood rots
12. pancakes cook
13. grass grows
14. the tree is cut down
15. food is digested
16. paper towel absorbs water

part iv - regents practice questions

1. what is a chemical property of sodium?

(a) soft metal, easily cut with a knife
(b) melts at a temperature of 98°c
(c) forms compounds with chlorine
(d) a silver - colored metal

1. which choice is one chemical and one physical change?

(a) freezing and melting
(b) freezing and evaporation
(c) burning and melting
(d) dissolving and breaking

1. which statement describes a chemical property of hydrogen gas?

(a) hydrogen gas burns in air.
(b) hydrogen gas is colorless.
(c) hydrogen gas has a density of 0.00009 g/cm³
(d) hydrogen gas has a boiling point of - 253°c

1. given the particle diagrams representing four molecules of a substance before and after a physical change has taken place:

Explanation:

Answer:

Part I: Physical change. Sodium polyacrylate absorbs water through a physical process of swelling without changing its chemical composition.
Part II:

1. P
2. P
3. P
4. P
5. C
6. P
7. P
8. P
9. C
10. P
11. P
12. P
13. P
14. C

Part III:

1. P
2. P
3. P
4. P
5. C
6. C
7. P
8. P
9. C
10. P
11. C
12. C
13. C
14. P
15. C
16. P

Part IV:

1. Reacts with water (or other valid chemical - property answer for sodium)
2. (d) Dissolving and cooking
3. Hydrogen gas burns in air (or other valid chemical - property answer for hydrogen gas)
4. The particles have the same chemical composition as before the physical change.