Question

new utrecht high school - regents chemistry mr. christodoulou
name: prt1
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.
it is a chemical change because the sodium polyacrylate turns into a snow - like substance and cant go back to its original powder like form
part ii - identify the following as a chemical (c) or physical property (p):
p 1. blue color

1. density
2. flammability
3. solubility (dissolves)

c 5. reacts with acid

1. supports combustion
2. sour taste
3. melting point
4. reacts with water
5. hardness

c 11. boiling point

1. luster
2. odor
3. reacts with air

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

1. nacl
2. ag (silver) tarnishes.

p 3. an apple is cut.
c 4. heat changes h2o to steam.
c 5. baking soda reacts to vinegar.

1. fe (iron) rusts forming iron oxide (feo).

c 7. alcohol evaporates.
c 8. ice melts.

1. milk sours.
2. sugar dissolves in water.
3. wood rots.

c 12. pancakes cook.
p 13. grass grows.
p 14. the tire is inflated.

1. food is digested.
2. paper towel absorbs water.

part iv - regents practice questions

1. which is a chemical property of sodium?

(a) soft metal, easily cut with a knife.
(b) melts at a temperature of 90°c
(c) forms compounds with chlorine
(d) silver colored metal

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

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

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 0.000 09g/cm3.
(d) hydrogen gas has a boiling point of - 250 °c.

1. given the particle diagram representing four molecules of a substance: which particle diagram best represents this same substance after a physical change has taken place?

Explanation:

Answer:

Part I: Chemical change because the sodium polyacrylate turns into a snow - like substance and can't go back to its original form.
Part II:

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

Part III:

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

Part IV:

1. C. forms compounds with chlorine
2. D. Dissolving and cooking
3. A. Hydrogen gas burns in air.
4. a