
Chemical changes create new substances –
called compounds
 New properties
 No resemblance to the chemicals making it
 Difficult to “undo” (can’t unbake a cake!)

Physical changes create mixtures
 No new substances form
 Properties of both can be found
 More easily undone…

“mixed” substances (WOW!) stuff jumbled
together
 they are not chemically combined - easy to
take apart
 Two types:
 Heterogeneous: parts can be SEEN and
SEPARATED
 Homogeneous: so well mixed you can’t
see its separate parts

Design a procedure that will allow you to
separate the following substances that have
been mixed together in a beaker:
 Sand (beach)
 Salt (Kosher)
 Pepper ((fresh) ground)
 Iron filings
 Paperclips
 Wood chips (like toothpick size)

A special type of homogeneous mixture
 “the best mixed” mixture possible
▪ ex: salt water
 Made of two parts:
Solvent: Stuff that does the dissolving
(water)
 Solute: Stuff that is being dissolved (salt)
 (water is known as the “Universal Solvent”)

How much of a given
solute dissolves in a
given amount of solvent
at a given temperature
Saturated solution: a
solution in which the
solvent can dissolve no
more solute at a given
temp.
 Super-saturated
solution: a solution
in which a solvent is
holding more than it
is supposed to…
these are very
unstable and
precipitate when
seeded or stressed