Thursday, September 13, 2013
How Can Density Be Used to Identify A
substance Lab
Bell Work 9/16

 What is the volume of a 36 g rock if its density is 25
g/ml?
 What is the mass of a brick if its density is 8.9g/cm3,
and the bricks dimensions are 2cm x 11cm x 8cm?
Agenda

 Discuss Classification of Matter
 Complete Classification Activity
Objectives

 Students will be able to:
 Classify matter into different categories
 Use density to identify a substance
Classification of Matter
Matter can be classified into many
different categories.
The next few slides we will be going over
each of these categories
Classification of Matter
 How are they similar? . . . Different?
Only one type
of matter in
sample
Water (H2O)
Muddy Water
Classification of Matter
 Pure Substance
Only one type
of matter in
sample
Water (H2O)
Classification of Matter
 Pure Substances – How are they different
Water (H2O)
Gold (Au)
Classification of Matter
 Pure Substances – Element
Atoms of only one
type are in the
substance
Gold (Au)
Classification of Matter
 Pure Substances – Compound
Atoms of more than
one type are in the
substance
Water (H2O)
Classification of Matter
 Mixture
Two or more
types of matter
in the sample
Chicken Soup
Classification of Matter
 Mixtures – How are they different?
Chicken Soup
Cola
Classification of Matter
 Heterogeneous Mixture
Mixture is not the
same throughout—
Can identify
different parts
Chicken Soup
Classification of Matter
 Homogenous Mixture
Mixture is the same
throughout
Cola
A. Matter Flowchart
MATTER
yes
MIXTURE
yes
Is the composition
uniform?
Homogeneous
Mixture
(solution)
PURE SUBSTANCE
no
Heterogeneous
Mixture
Colloids
no
Can it be physically
separated?
yes
Can it be chemically
decomposed?
Compound
Suspensions
Element
no
A. Matter Flowchart
 Examples:
 graphite
 pepper
• Element
• Hetero. Mixture
 sugar (sucrose)
• Compound
 paint
• Hetero. Mixture
 soda
• Homo. Mixture
B. Pure Substances
 Element
 composed of identical atoms
 EX: copper wire, aluminum foil
B. Pure Substances
 Compound
 composed of 2 or more
elements in a fixed ratio
 properties differ from those
of individual elements
 EX: table salt (NaCl)
Compound Example
C. Mixtures
 Variable combination of 2 or more pure
substances.
Heterogeneous
Homogeneous
Tyndall Effect
 https://www.youtube.com/watch?v=S
oUmz8L87Z4
C. Mixtures
 Solution
 homogeneous
 very small particles
 no Tyndall effect
 particles don’t settle
 EX: rubbing alcohol
Tyndall Effect
C. Mixtures
 Colloid
 heterogeneous
 medium-sized particles
 Tyndall effect
 particles don’t settle
 EX: milk
C. Mixtures
 Suspension
 heterogeneous
 large particles
 Tyndall effect
 particles settle
 EX: fresh-squeezed
lemonade
C. Mixtures
 Examples:
 mayonnaise
colloid
 muddy water
suspension
 fog
colloid
 saltwater
solution
 Italian salad
dressing
suspension
Physical vs. Chemical Properties
 Physical Property
 Can be observed without changing the
identity of the substance
 Chemical Property
 Describes the ability of a substance to
undergo changes in identity
B. Physical vs. Chemical
Properties
 Examples:
 melting point
physical
 flammable
chemical
 density
physical
 magnetic
physical
 tarnishes in air
chemical
Physical vs. Chemical Change
 Physical Change
 Changes the form of a substance without
changing its identity
 Properties remain the same
 Reversible
 Chemical Change
 Changes the identity of a substance
 Products have different properties
 Irreversible
Physical vs. Chemical Change
 Signs of a Chemical Change
 change in color or odor
 formation of a precipitate (solid)
 formation of a gas
 change in light or heat
Physical vs. Chemical Change
 Examples:
 rusting iron
chemical
 dissolving in water
physical
 burning a match
chemical
 melting ice
physical
 grinding salt
physical
Classifying Matter Activity
 Get out a sheet of paper and put your
name on the top.
 Create a data chart with the following
headings
Vial
Number
Name of
Material
Pure
Substance or
Mixture
Element,
Compound,
Hetero or Homo
geneous
Reasoning
(Why did you
classify it as
this?)
 Make 20 rows and label 1-20 in the column
“vial number”
Classifying Matter Activity
 You will pair up and sit with your partner
on one side of each lab table with 1 group
at the back table if needed.
 I will come give you a vial with matter in
it, you will write the name of the matter in
the appropriate column, decide whether it
is a pure substance or a mixture and then
what type of pure substance or mixture.
Then pass it on to the next group
Analysis
1. Which classification was hardest to determine-
Element, Compound, Heterogeneous or
Homogenous? Why was this the hardest one?
2. If you had to separate the heterogeneous
mixtures into colloids or suspensions, what
property would you look at to separate the two?
3. Determine whether each sample below is an
element, compound, heterogeneous or
homogeneous mixture

A
B
C
D
E