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Each
substance has a unique set of physical and chemical properties that
identifies that substance
PHYSICAL
PROPERTY
A
property that can be observed without changing the nature of the substance
-
Mass
- amount of matter in an object
-
Volume
- amount of space an object occupies
-
Density
- mass per unit volume
-
Boiling
Point - temperature at which
a liquid's vapor pressure equals atmospheric pressure
-
Freezing
Point - temperature at which
a liquid changes into a solid
-
Shininess
- tendency of an object to reflect light without scattering it
-
Conductivity
- tendency to allow the flow of heat or electricity
-
Ductility
- ability to be stretched into wires
-
Malleability
- ability to be shaped
CHEMICAL
PROPERTY
A
property that can be observed only if the substance undergoes a change
into another substance
- Reactivity
with air (oxygen)
- Reactivity
with a acid, reactivity with a base
- Corrosiveness
or ability to be corroded
- Flammability
- Reactivity
with another element or compound to produce a different compound
EXTENSIVE
VS. INTENSIVE PROPERTIES
EXTENSIVE
PROPERTIES
-
Depends
on the amount of the sample
-
Changes
from sample to sample (different)
-
Not
usually useful for identifying substances
-
Examples:
volume, mass, weight, length
INTENSIVE
PROPERTIES
-
Independent
of the amount of the sample
-
Same
for every sample; useful for identifying substances
-
Examples:
color, density, boiling point
-
Only
physical properties change in a physical change - a change in size,
the state or the shape of matter
-
No
new substances are formed - no change in the type of element, compound,
atom, or molecule
-
After
the physical change, you have the same substance you began with
- no chemical change has occurred
-
Reversible
by ordinary physical means
- Examples:
change of state (gas, liquid, solid), grinding,
making solutions, dissolving a solid in a liquid
-
New
substances with new properties are formed; chemical and physical
properties change
-
These
changes are not easily reversed
-
Evidences
of Chemical Change:
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