2.2 PHYSICAL PROPERTIES
n
Vocabulary:
n
n
n
n
physical property
viscosity
conductivity
n
n
n
malleability
melting point
boiling point
n
n
n
filtration
distillation
physical change
Objectives:
n
n
n
n
n
Describe physical properties of matter.
Identify substances based on their physical properties.
Describe how properties are used to choose materials.
Describe methods used to separate mixtures.
Describe evidence that indicates a physical change has
taken place.
Chapter 2 Properties of Matter
1
EXAMPLES OF PHYSICAL
PROPERTIES
v
physical property - any characteristic of a
material that can be observed or measured
WITHOUT changing the composition of the
substances in the material
v
examples of physical properties:
v
viscosity
v
melting point
v
density
v
conductivity
v
boiling point
v
hardness
v
malleability
Chapter 2 Properties of Matter
2
EXAMPLES OF PHYSICAL
PROPERTIES: VISCOSITY
v  viscosity
- tendency of a liquid to keep from
flowing (its resistance to flowing)
v  greater
viscosity, slower liquid moves
v  usually
decreases
when heated
Chapter 2 Properties of Matter
3
EXAMPLES OF PHYSICAL
PROPERTIES: CONDUCTIVITY
Which spoon should you use to stir a pot of
soup heating on a stove: a metal spoon or a
wooden spoon? Why?
Chapter 2 Properties of Matter
4
EXAMPLES OF PHYSICAL
PROPERTIES: CONDUCTIVITY
Answer:
The wooden spoon
Why?
Because wood is not a good
conductor of heat. A metal
spoon is a good conductor
of heat.
Chapter 2 Properties of Matter
5
EXAMPLES OF PHYSICAL
PROPERTIES: CONDUCTIVITY
v  conductivity
- material s ability to allow heat
to flow
v  if
a material is a good conductor of heat, it is
usually also a good conductor of electricity.
Chapter 2 Properties of Matter
6
EXAMPLES OF PHYSICAL
PROPERTIES: MALLEABILITY
v  malleability
- ability of a solid to be
hammered without shattering
v  most
metals are malleable (e.g. gold)
Chapter 2 Properties of Matter
7
EXAMPLES OF PHYSICAL
PROPERTIES: MALLEABILITY
v  not
malleable (instead brittle) - ice, glass
Chapter 2 Properties of Matter
8
EXAMPLES OF PHYSICAL
PROPERTIES: HARDNESS
v  hardness
v  one
way to compare hardness of 2 materials
is to see which can scratch the other
v  diamonds
are hardest
known material
Chapter 2 Properties of Matter
9
EXAMPLES OF PHYSICAL
PROPERTIES: MP & BP
v  melting
point - temperature at which a
substance changes from solid to liquid
v  boiling
point - temperature at which a
substance boils
v  example:
water s melting point is 0°C
& its boiling point is 100°C.
Chapter 2 Properties of Matter
10
EXAMPLES OF PHYSICAL
PROPERTIES: MP & BP
Chapter 2 Properties of Matter
11
EXAMPLES OF PHYSICAL
PROPERTIES: DENSITY
v  density
- ratio of the mass of a substance to
its volume
Mass (g)
Density =
Volume (cm3)
how heavy a substance is compared to its size
v  example:
v  can
density of silver is 10.5g/cm3
be used to test the purity of a substance
Chapter 2 Properties of Matter
12
USING PHYSICAL PROPERTIES
physical properties are used to:
v  identify a material
v  choose a material for a specific purpose
(look at How it Works: Making a Sculpture on page 49)
v  separate
a substance in a mixture
(basis for lab on Thursday)
Chapter 2 Properties of Matter
13
USING PHYSICAL PROPERTIES
TO SEPARATE A MIXTURE
2 common separation methods are:
v  filtration
- process that separates materials
based on the size of their particles
Chapter 2 Properties of Matter
14
USING PHYSICAL PROPERTIES
TO SEPARATE A MIXTURE
2 common separation methods are:
v  filtration
- process that separates materials
based on the size of their particles
Chapter 2 Properties of Matter
15
USING PHYSICAL PROPERTIES
TO SEPARATE A MIXTURE
2 common separation methods are:
v  distillation - process that separates
substances in a solution based on their
boiling points
Chapter 2 Properties of Matter
16
SEPARATION OF MIXTURES
Methods based on physical properties
Filtra$on – based on size Dis$lla$on – based on boiling point Chapter 2 Properties of Matter
17
RECOGNIZING PHYSICAL
PROPERTIES
v
physical change - change that occurs when
some of the properties of a material change,
but the substances in the material remain the
same.
v
some physical changes can be reversed while
others cannot
v
e.g. water changing states, melting butter, cutting
food, cutting hair
Chapter 2 Properties of Matter
18