Download LECTURE_GasLaws1(3)

CLASSIFYING MATTER
Substance (pure): made up of only one kind
of matter; every particle has the same fixed
composition and properties
1.
a. Elements
Au, Na, He, N
b. Compounds: a substance that contains two or more elements
chemically combined in a fixed proportion.

C6H12O6, H2O

Compounds can be broken down into simpler
substances by chemical means. Elements cannot.


The properties of a compound are different from the properties of
the elements from which it was created – e.g. NaCl
CLASSIFYING MATTER
2. Mixture: physical blend of two or more
components.
Example: salt-sand mixture



The basic identity of each substance is not changed.
Properties are not the same throughout.
Can be separated into its components by physical
processes.
TYPES OF MIXTURES
 Heterogeneous:
composition is not uniform
throughout.


Often components are large enough to be seen.
Example: Pizza
 Homogeneous:
constant composition
throughout, but the amount of each substance can
vary.
 Examples: sugar water, vinegar
Solutions: liquid or gaseous mixtures
 Alloys: solid solutions of metals


Examples: steel, brass, bronze
LABEL AS SUBSTANCE OR MIXTURE:
IF SUBSTANCE, ELEMENT OR COMPOUND?
IF MIXTURE, HETERO- OR HOMOGENEOUS?
1. Salt water
 2. vinegar
 3. sugar
 4. sodium
 5. orange juice & pulp

6. blood
 7. hamburger
 8. aluminum foil
 9. iron
 10. air

PHYSICAL CHANGE
 Physical
Change: a change in matter
that does not involve a change in the
identity of individual substances.


Dissolving
Changes in state
CHEMICAL CHANGE
 Chemical
Change (Chemical
Reaction): the change of one or more
substances into new substances.


REACTANTS  PRODUCTS
Involves the rearrangement of atoms.
Law of Conservation of Mass: no atoms are
created or destroyed during a chemical
reaction.
 Mass of Reactants = Mass of Products
LABEL AS A “PHYSICAL” OR
“CHEMICAL” CHANGE.
change in shape
- physical
 rusting of iron
- chemical
 explode
- chemical
 cutting a sheet of paper
– physical
 breaking a crystal
– physical
 corrode
- chemical
 Bend
- physical
 Oxidize
- chemical

tarnish
– chemical
 grind
- Physical
 melt
- physical
 boil
- physical
 ferment
- chemical
 salt dissolving in water
- - physical

RECOGNIZING CHEMICAL CHANGES
Transfer of Energy -- Heat or Light is released or
absorbed.
 Change in Color (drastic)
 Production of a Gas (excluding changes in
physical state and dissolved gases – e.g. opening
a carbonated soda)
 Formation of a Precipitate (a solid that forms
and settles out of a liquid mixture – e.g. soap
scum)
