Physical and Chemical Changes

1. Matter and Change

2. B. Physical Properties
 1. can be observed
without changing the
chemical composition
 2. Examples
 Color
 Melting point
 Density
 Hardness
 Malleability

3. C. Chemical Properties
 1. determined by how a
chemical reacts (or
doesn’t) with another
chemical
 2. Examples –
 Rusts
 Reacts with HCl
 Reacts with water

4. Physical or Chemical Property?
 7) Water boils at 100°C.
 8) Zinc reacts with hydrochloric acid.
 9) Sodium chloride dissolves in water.
 10) Aluminum is shiny silver in color.
 11) Copper is ductile.
 12) Calcium reacts with water.
 13) The density of aluminum is 2.7 g / mL.

5. D. States of Matter
Solids
 a) definite mass?
 b) definite volume?
 c) definite shape?
 d) compressible?
 e) able to flow?

6. D. States of Matter
Liquids
 a) definite mass?
 b) definite volume?
 c) definite shape?
 d) can be compressed?
 e) flows?

7. D. States of Matter
Gases
 a) definite mass?
 b) definite volume?
 c) definite shape?
 d) can be compressed?
 e) flows?

8. D. States of Matter
1) summary chart
Property Solid Liquid Gas
Mass Fixed Fixed Fixed
Volume Fixed Fixed Volume of
container
Flows? No Yes Yes
Shape Fixed Shape of container Shape of container
Compressible? No No yes
Expands? No No yes

9. D. States of Matter
2) Vapors
 a) = substances in the
gaseous state which are
usually in the liquid or
solid state at room
temperature
 b) ex. – gasoline fumes,
moth ball odors, steam,
“fog” from dry ice

10. E. Classification of Matter
 1. Substances
= definite or fixed
composition
 can write a chemical
formula for it
 pure

11. E. Classification of Matter
 1. Substances
 a) Elements
 Listed on periodic table
 Mg, Ne, Cl, C, etc.

12. E. Classification of Matter
 1. Substances
 b) Compounds
 Contain two or more
elements in fixed ratio
 Ex. – NaCl, CO, H2O

13. E. Classification of Matter
 2. Mixtures
= composition is NOT fixed
or definite; it varies
 Cannot write a formula for
it

14. E. Classification of Matter
 2. Mixtures
 a) homogeneous mixtures
*uniform (same
throughout)
*one phase
*also called solutions
(but can be s, l or g)
*ex. – saline solution, tap
water, brass, hot tea, air

15. E. Classification of Matter
 2. Mixtures
 b) heterogeneous
mixtures
 *not uniform
 *two or more phases
 *ex. – soil, fresh-squeezed
orange juice, sand and
water

16. F. How to separate parts of a mixture?
 1. Magnetism

17. F. How to separate parts of a mixture?
 2. Filtration

18. F. How to separate parts of a mixture?
 3. Density

19. F. How to separate parts of a mixture?
 4. Distillation
 (different boiling points)

20. F. How to separate parts of a mixture?
 5. Chromatography
 (ex. – paper + ink)

21. G. Changes
 1. Physical Changes
 a) chemical composition
of material does NOT
change
 b) may be reversible
 c) examples
 Tearing paper
 Boiling water
 Crushing salt
 Crumpling foil

22. G. Changes
 2. Chemical changes
 a) change in chemical
composition
 b) examples
 Iron rusting
 Zinc + hydrochloric acid
 Digestion of food
 Burning wood
 Lithium + water

23. H. Clues for a chemical change (reaction)
 1. formation of bubbles
(gas)
 Ex. – metal + acid

24. H. Clues for a chemical change (reaction)
 2. formation of
precipitate (insoluble
powder)

25. H. Clues for a chemical change (reaction)
 3. release or absorption
of energy (heat or light)
 Ex. – burning of wood

26. H. Clues for a chemical change (reaction)
 4. change in color
 Ex. – meat changes color
when cooked
 Ex. – changing in color of
leaves in fall

27. H. Clues for a chemical change (reaction)
 5. change in pH
(acidity level)

28. I. Sometimes the “clues” indicate a physical change!
 1. color change could be
dilution (ex. – add water
to Kool-Aid)
 2. bubbles could be
boiling liquid
 3. heat absorbed during
a change in state (ex. -
melting ice)

29. J. Law of
conservation
of mass
1. Mass cannot be
created or destroyed in
a chemical reaction or
physical change