1. Chemical Properties & Physical and Chemical Changes

2. Physical changes are those changes that do not result in the production of a new substance.  If you melt a block of ice, you still have H2O at the end of the change.   

3. If you break a bottle, you still have glass
If you break a bottle, you still have glass.  Painting your nails will not stop them from being fingernails.  Some common examples of physical changes are: melting, freezing, condensing, breaking, crushing, cutting, and bending.

4. When a change of state occurs,
molecules or atoms may move
faster or slower, may spread out
or clump together, but they do not
change.
i.e. An H2O molecule is still an H2O molecule!

5. Some, but not all physical changes can be reversed
Some, but not all physical changes can be reversed. You could refreeze the water into ice, but you cannot put your hair back together if you don’t like your haircut!

6. Special types of physical changes where any object changes state, such as when water freezes or evaporates, are sometimes called change of state operations.

7. The distinction between physical and chemical change.
Physical change
A substance alters its physical form, not its composition
Chemical change
A substance is converted into a new substance

8. Lithium (Li) is a soft, gray solid that has the lowest density
Sample Problem 1.5
Calculating Density from Mass and Length
PROBLEM:
Lithium (Li) is a soft, gray solid that has the lowest density
of any metal. If a slab of Li weighs 1.49 x 103 mg and has
sides that measure 20.9 mm by 11.1 mm by 11.9 mm, what is the density of Li in g/cm3 ?

10. CHEMICAL PROPERTIES
Chemical properties can ONLY be observed AS the substances are changing into different substances.

11. Chemical changes, or chemical reactions, are changes that result in the production of a new substance. 

12. FLAMMABILITY: A material’s ability to BURN in the presence of OXYGEN A chemical property

13. REACTIVITY: How readily (easily) a substance combines chemically with other substances. A chemical property

14. Some Characteristic Properties of Copper
Table 1.1
Some Characteristic Properties of Copper
Physical Properties
Chemical Properties
slowly forms a basic blue-green
sulfate in moist air
reddish brown, metallic luster
easily shaped into sheets
(malleable) and wires
(ductile)
reacts with nitric acid
and sulfuric acid
good conductor of heat
and electricity
density = 8.95 g/cm3
slowly form a deep-blue
solution in aqueous ammonia
melting point = 10830C
boiling point = 25700C

15. When you burn a log in a fireplace, you are carrying out a chemical reaction that releases carbon.  When you light your Bunsen burner in lab, you are carrying out a chemical reaction that produces water and carbon dioxide. 

16. Common examples of chemical changes that you may be somewhat familiar with are; digestion, respiration, photosynthesis, burning, and decomposition. 

17. Physical or Chemical Change?
Painting Wood
PHYSICAL

18. Physical or Chemical Change?
Burning Paper
CHEMICAL

19. Physical or Chemical Change?
Digestion of food
CHEMICAL

20. Sugar dissolving in water PHYSICAL
Physical or Chemical Change?
Sugar dissolving in water
PHYSICAL

21. Iron turning red when heated PHYSICAL
Physical or Chemical Change?
Iron turning red when heated
PHYSICAL

22. Physical or Chemical Change?
Evaporation
PHYSICAL

23. A pond freezing in winter PHYSICAL
Physical or Chemical Change?
A pond freezing in winter
PHYSICAL

24. Physical or Chemical Change?
Melting ice
PHYSICAL

25. Physical or Chemical Change?
Cutting wire
PHYSICAL

26. Physical or Chemical Change?
Painting fingernails
PHYSICAL

27. Physical or Chemical Change?
Cutting fabric
PHYSICAL

28. Physical or Chemical Change?
Baking muffins
CHEMICAL

29. Physical or Chemical Change?
Shattering glass
PHYSICAL

30. Decomposition of old leaves CHEMICAL
Physical or Chemical Change?
Decomposition of old leaves
CHEMICAL

31. Physical or Chemical Change?
Wrinkling a shirt
PHYSICAL

32. Physical or Chemical Change?
An old nail rusting
CHEMICAL

33. Common Decimal Prefixes Used with SI Units
Table 1.3

34. Densities of Some Common Substances*
Table 1.5
Substance Physical State Density (g/cm3)
Hydrogen
Gas
Oxygen
Gas
Grain alcohol
Liquid
0. 789
Water
Liquid
0.998
Table salt
Solid
2.16
Aluminum
Solid
2.70
Lead
Solid
11.3
Gold
Solid
19.3
*At room temperature(200C) and normal atmospheric pressure(1atm).

35. Physical versus Chemical Properties
Unit II - Part 1
The study of matter 35

36. Reviewing MATTER Matter: anything that has mass and takes up space
Mass – the amount of matter in something
Volume – the amount of space something occupies
Which of the following is matter?
A car?
A box?
You? 36

37. What is a property?
Property: a characteristic of a substance that can be observed 37

38. Physical Property
Physical property: a property that can be observed without changing the identity of the substance.
Examples:
luster
malleability: the ability to be hammered into a thin sheet
ductility: the ability to be stretched into a wire
melting point
boiling point
density
solubility
specific heat 38

39. • In a physical change no new substances
are formed
• Physical changes include changes of
state.
• liquid to solid: Solidifying or Freezing
• solid to liquid: Melting
• liquid to gas: Evaporation or Boiling
• gas to liquid: Condensation
• gas to solid or solid to gas: Sublimation

40. Special Physical Properties
Melting point: the temperature at which a substance changes from a solid to a liquid at a given pressure
water = 0oC
Boiling point: the temperature at which a substance changes from a liquid to a gas at a given pressure
water = 100oC 40

41. Chemical Properties
Chemical property: a property that can only be observed by changing the identity of the substance
Examples:
flammability
ability to rust
reactivity with vinegar 41

42. Density Density is the amount of mass per unit of volume.
Density can be used to identify a substance.
The density of water is 1.0g/mL 42

43. Density Calculations Calculations:
D = m/V = g/mL = g/cm3
Ex: A cube has a mass of 2.8 g and occupies a volume of 3.67 ml. Would this object float or sink in water?
Mass = 2.8 g Volume = 3.67 mL
D = 2.8g/3.67 mL= 0.76 g/mL
This object would float in water because its density is less than water (1.0 g/mL). 43

44. More Density Calculations
Ex: A liquid has a mass of 25.6 g and a volume of 31.6 mL. Use the table below to identify the substance.
M=25.6 g V=31.6 mL
D = 25.6 g/31.6 mL
D= 0.81 g/mL
The substance is ethanol. 44

45. Rules for Rounding Off Numbers
1. If the digit removed is more than 5, the preceding number increases by 1.
5.379 rounds to 5.38 if three significant figures are retained and to 5.4 if two significant figures are retained.
2. If the digit removed is less than 5, the preceding number is unchanged.
rounds to if three significant figures are retained and to 0.24 if two significant figures are retained.
3.If the digit removed is 5, the preceding number increases by 1 if it is odd and remains unchanged if it is even.
17.75 rounds to 17.8, but rounds to 17.6.
If the 5 is followed only by zeros, rule 3 is followed; if the 5 is followed by nonzeros, rule 1 is followed:
rounds to 17.6, but rounds to 17.7
4. Be sure to carry two or more additional significant figures through a multistep calculation and round off only the final answer.

46. Clues that a Chemical Change has occurred.
• Color change
• Heat or light given off
• Odor given off
• Gas released
• Solid forming in a liquid