Aim: How do compounds differ from mixtures?
Mixture - consist of elements and/or compounds physically combined.
Compounds
1) Formed by:
example:
Chemical Change
Physical Change
copper sulfate
“copper” penny
element + element
Cu
2) Properties of
components:
Cu
gold colored
S
yellow
Mixtures
+
element
S
Change
O
Don’t Change (They are retained.)
The props of the mixture is a combination
of properties of its components.
O
colorless
CuSO4
blue
Cu
gold colored
Zn - silver colored
3) Composition:
CuSO4
Definite
Cu =40%, S=20%, O=40%
CuSO4 = CuS = CuO
*Must be the same in every sample.
Indefinite
In 1837: U.S. penny = 100% pure Cu
In 1982: 97.5% Zn, 2.5% Cu
Today: ???? It’s up to the Treasury Dept.
* Can differ from sample to sample.
4) Broken
down by:
Demo:
Chemical Change
copper sulfate + lead nitrate
lead sulfate
+ copper nitrate
Physical Change
Demo: Penny
Add HEAT
Zn (l)
Cu (s)
mp = 693 K
mp = 1358 K
(See Table S)
As a result, the Zn melts 1st and drips
out of the Cu jacket!