Kinds of Solutions:.
I
An. unsaturated solution is one in which still more
solute can dissolve
into the solvent at spedfic temperature and pressure
conditions. An
unsaturated solution for a particular solute is indicated
by any point in
the region under the solute’s solubility curve.
•
2.
A saturated solution is one containing the maxmim
un quantity of a
solute at specific temperature and pressure condition
s, it is the
maximum solute concentration. The quickest way
to identify a
saturated solution is to look for the presence of undi
ssolved solids in
the solution. A saturated solution is indicated by any
point on the
solubility curve of that solute.
3.
A supersaturated solution is a solution containing more
dissolved
solute than it could normally dissolve at a particular
temperature and
pressure. Any point in the region above the solubility
curve represents
a supersaturated solution. The supersaturated condition
is an unstable
situation.
Solubility and Solubilitv Curves
The solubility of a solute is a physical, quantitative prop
erty of a solute. It is
the concentration of a saturated solution of a solute at a
specific temperature
and pressure. Every pure substance has its own uniq
ue” solubility
Units for solubility are: grams of solute
100 mL of solvent
60
50O
3:
SUPERSATURATED
(above the line)
,400
tD
4-,
0
(I)
UNSATUNATED
(under the line)
0
0)
0)
0
25
50
75
100
Temperature (°C)
Solid Solutes: Usually have higher solubilitywith high
er temperatures.
Gaseous Sdutes: Always have higher solubility with
lower temperatures.
Lkiuid Salutes: Difficult to generalize.
_____
___
_____________
___
Solubility Curves
Answer the following questIOns
ased on the solubility curve
below.
1.
Which salt is least soluble in
water at 20° C?
_
150
—
*
—
—
—
00t
x
0)
d
120””7
1’0-——-7-100
7
-
—
—
—
(4.
How many grams of
potassium chloride can be
dissolved in 200 g of water at
80° C?
At 40° C. how much
potassium nitrate can be
dissolved in 300 g of water?
—
9G7
\
-
/
—
—
—
—
604\
EiTh
\i
,/
2G7
1:
‘I
20 30
40 50 60 70 80 90 100
Temperature (0°C)
cj
5. At 3000,90 g of sodium nitrate is
dissolved in 100 g of
water. Isthis solution saturated, unsat
urated or
supersaturateq?______________
__
6. A saturated solution of potassium
chlorate is formed from
one hundred grams of water. If the
saturated solution is
cooled from 80° C to 50° C, how ma
ny grams of precipitate
are formed?
7. What compound shows a decre
ase in soluhility from
10
C?
8.
Which salt is most soluble at 10° C?
9. Which salt is least soluble at 500 C?
L
Which salt is least soluble at 90° C?
—
°
Which salt shows the least change in
solubilily from
00_10000?
0°
-
80
—
3.
—
:•::::::
70
2.
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—
00
to