Physical Properties

1
Physical Properties Density
2
Physical Properties

• How would you describe someone or something?
• The weight, height, length, eye color, hair
  color, etc. would be good items to use to
  describe someone.
• It is easy to identify chemicals, compounds and
  elements based on their physical properties also.
• These include color, odor, and state of matter to
  name a few.

3
Mass

• A physical property that every object possesses
  is mass. The amount of mass in a person will
  never change when the object is moved from place
  to place.

4
Weight

• A physical property that is related to
  mass is weight. The weight of a dog will change
  if it is moved to Uranus because weight is
  determined by gravity.

5
Gravity

• The greater the mass of an object, the more
  strongly it attracts other objects. The weight of
  a dog would be heavier on earth than on the moon,
  because the earths mass is larger than the
  moons

6
Physical Changes

• Some physical changes would be
• boiling of a liquid
• melting of a solid
• dissolving a solid in a liquid to give a
  homogeneous mixture a SOLUTION.

Physical changes do not change the identity of
Substances
7
Chemical Change
Click for movie
2 H2(g) O2 (g) -- 2 H2O(g)
8
Chemical Change

• Burning hydrogen (H2) in oxygen (O2) gives H2O.

• Chemical change or chemical reaction
  transformation of one or more atoms or molecules
  into one or more different molecules.

9
Density

• Another physical property that can be used is
  density.
• Density is a measure of the relationship between
  mass and the volume it occupies.
• Think of it like using weight and height for
  babies
• 95th percentile for height, 30th for weight

10
DENSITY - an important and useful physical
property
Platinum
13.6 g/cm3
21.5 g/cm3
2.7 g/cm3
11
Buoyancy and Density

• One factor that density controls is floating and
  sinking.
• Objects float and sink because of their density.
• The density of water is 1.0 g/mL.
• The density of cork is 0.34 g/mL.
• The density of lead is 13.9 g/mL.

12
Buoyancy and Density

• Compounds that are less dense than water float.
• Name some other items that will float in water.
• Compounds that are more dense than water sink.
• Name some other items that will sink in water.

13
Density Units

• Density can be defined as the unit mass per unit
  volume.
• Density Mass/Volume
• Density is recorded as g/mL.
• Mass is measured in g.
• Volume is measured in mL.

14
Density Units

• Density, Mass, / Volume,
• g/mL g / mL
• You may have to convert to get the units correct.
  Do this before you divide.

15
Density

• What is the density of 5.0 g of tin that has a
  volume of 1.2 mL?
• Density Mass / Volume
• ? g/mL 5 g / 1.2 mL
• 4.2 g/mL

16
Density

• What is the volume of 5.0 g of tin that has a
  density of 4.6 g/mL?
• Density Mass / Volume

I prefer to solve for the unknown before putting
in the numbers and units. (Less writing)
17
Density

• X 5 g / 4.6 g/mL

Grams cancel out and you are left with mL. Try
the math.

• X 1.1 mL

If at this time while doing other problems, if
the units are not correct, you are wrong and need
to restart the problem
18
Lab Results

• Density of rectangular bars
• Density of granite

19
Density of Some Common Substances

• Substance Density (g/cm3)  
• Air 0.0013
• Feathers 0.0025
• Wood(Oak) 0.6 - 0.9
• Ice  0.92 
• Water  1.00
• Bricks  1.84
• Aluminum  2.70
• Steel  7.80
• Silver  10.50
• Gold  19.30 

Answers from density lab Brass, iron, copper,
and aluminum
20
Density Review
21
Floating Liquids

• Which diagram represents the liquid layers in
  the cylinder?
• (K) Karo syrup (1.4 g/mL), (V) vegetable oil
  (0.91 g/mL,) (W) water (1.0 g/mL)
• 1) 2) 3)

K
W
V
V
K
W
W
V
K
22
Solution

• (K) Karo syrup (1.4 g/mL), (V) vegetable oil
  (0.91 g/mL,) (W) water (1.0 g/mL)
• 1)

V
W
K
23
PROBLEM Mercury (Hg) has a density of 13.6
g/cm3. What is the mass of 95 mL of Hg?

• Convert volume to mass

Note 1 ml is the same as 1 cm3
24
Bloody Density

• If blood has a density of 1.05 g/mL, how many
  liters of blood are donated if 575 g of blood are
  given?
• 1) 0.548 L
• 2) 1.25 L
• 3) 1.83 L

Caution The units are liters!
25
Solution

• 1)
• Unit Plan g mL L
• 575 g x 1 mL x 1 L 0.548
  L
• 1.05 g 1000 mL

26
Light or Heavy Metals

• You have 3 metal samples. Which one will
  displace the greatest volume of water?
• 1 2 3
• Discuss your choice with another student.

25 g Al 2.70 g/mL
45 g of gold 19.3 g/mL
75 g of Lead 11.3 g/mL
27
Solution

• 1) 25 g Al x 1 mL 9.2 mL
  2.70 g

25 g Al 2.70 g/mL