SOLUBILITY
Let’s Review some vocabulary!
solubility: The ability to dissolve a substance in
water.
solute: The substance being dissolved.
solvent: The substance that the solute is being
dissolved in.
Water is considered the universal solvent! Why?
solution: A mixture made of solute(s) and a
solvent.
Solutions
Some solutions are good conductors of
electricity.
To understand conductivity of solutions
we need to review covalent vs. ionic
bonds:
Conductivity of Solutions
• Ionic bonds tend to break up in water,
covalent bonds don't.
• This is b/c the charged ions are attracted
to the opposite partial charges on the
water molecules. So the ionic compound is
pulled apart in the water!!!
• When the ionic bonds break, they leave the
ions floating around in the water as
charged particles. That's important…
Conductivity of Solutions
• It’s important b/c electricity is carried by
charged particles. So, a good conductor of
electricity would be a sodium ion, Na+, or a
chlorine ion, Cl-. (See where this is going?)
• Covalent bonds do not have charged particles.
• So solutions that have an ionic compound as
a solute will conduct electricity well!!!
Solubility Curves (Graphs)
Solubility varies from one substance to
the next.
Therefore, we have solubility curves…
graphs of solutes regarding the amount
that will dissolve in a certain amount of
solvent.
Solubility Curve
How much KNO3 can be dissolved at 70oC in 100 cc of water?
Solute (g) dissolved in 100ml of
water
200
120 g
180
160
140
120
NaCl
KCl
KNO3
100
80
60
40
20
0
0
10
20
30
40
50
60
70
o
Temperature of Solvent C
80
90
100
Reading a Solubility Curve
Where the solutes cross they are
equally soluble at that temperature.
Amount of Solute dissolved is on the Y-AXIS)
(Remember: Temp. is on the X-AXIS
At what temperature are the solutes equally soluble?
Solubility Curve
Solute (g) dissolved in 100ml of
water
200
180
160
140
120
NaCl
KCl
KNO3
100
80
60
40
20
0
0
10
20
30
40
50
60
70
80
90
100
o
Temperature of Solvent C
28 oC (If you said 38, you were reading the wrong axis!)
How much KNO3 can be dissolved at 50oC in 100 cc of water?
Solubility Curve
Solute (g) dissolved in 100ml of
water
200
180
160
140
120
NaCl
KCl
KNO3
100
80
60
40
20
0
0
10
20
30
40
50
60
70
80
o
Temperature of Solvent C
About 75 g (Don’t forget units!!!)
90
100
Q: At what temperature can 52 g of KCl be dissolved?
Solubility Curve
Solute (g) dissolved in 100ml of
water
200
180
160
140
120
NaCl
KCl
KNO3
100
80
60
40
20
0
0
10
20
30
40
50
60
70
80
o
Temperature of Solvent C
80
o
C (Don’t forget units!!!)
90
100
Q: How much NaCl can be dissolved at 60oC?
Solubility Curve
Solute (g) dissolved in 100ml of
water
200
180
160
140
120
NaCl
KCl
KNO3
100
80
60
40
20
0
0
10
20
30
40
50
60
70
o
Temperature of Solvent C
39 g
80
90
100
Reading a Solubility Curve For
Gases
• The solubility curve for gases
are the opposite of the solubility curve
for solids.
Solid
graph
Gas
graph
• The solubility of a gas decreases as the
temperature increases.
Solubility Curve w/ Gases
Which substances on the graph are gases?
Solute (g) dissolved in 100ml of
water
200
180
160
140
120
NH3 (gas)
KCl
KNO3
HCl (gas)
100
80
60
40
20
0
0
10
20
30
40
50
60
70
o
Temperature of Solvent C
NH3 and HCl
80
90
100
Solubility Curve w/ Gases
Q: How much NH3 can be dissolved at 65oC?
Solute (g) dissolved in 100ml of
water
200
180
160
140
120
NH3 (gas)
KCl
KNO3
HCl (gas)
100
80
60
40
20
0
0
10
20
30
40
50
60
70
o
Temperature of Solvent C
20 g
80
90
100
Solubility Curve w/ Gases
At what temperature can 60 g of HCl be dissolved?
Solute (g) dissolved in 100ml of
water
200
180
160
140
120
NH3 (gas)
KCl
KNO3
HCl (gas)
100
80
60
40
20
0
0
10
20
30
40
50
60
70
o
Temperature of Solvent C
45 oC
80
90
100
Saturated Solutions
Saturation is when something has
dissolved in a solution and no more of it
will dissolve under normal circumstances.
It has reached equilibrium.
Unsaturated Solutions
Unsaturated is just before the
equilibrium is reached, so you can keep
dissolving the substance into the
solution.
Supersaturated Solutions
• Supersaturated is when you change the
conditions so that you can dissolve more of
the substance into the solution than it
normally would.
• If the solution is brought back under normal
conditions, it will spit back out the substance.
(Coca-cola is an example of a super saturated
solution of CO2, when a bottle is opened it will
attempt to reach equilibrium again by
bubbling and fizzing. When it does
reach equilibrium it becomes flat)
• Another example is Rock Candy
Solubility Curve
Solute (g) dissolved in 100ml of
water
200
180
Super saturated
160
140
Saturated
120
100
NaCl
KCl
KNO3
Unsaturated
80
60
40
20
0
0
10
20
30
40
50
60
70
o
Temperature of Solvent C
80
90
100
Factors that Affect
Solubility
There are three main factors that will
cause the rate of solubility (how fast a
solute dissolves) to increase.
Can you guess what they might be?
1. Stirring
2. Heating the solution
3. Increasing the surface area of the solute
1. A mixture made of solute and
solvent is called a:
Solution
Solvent
Saturated
Solubility
65%
20%
15%
ili
ty
lu
b
So
Sa
tu
ra
t
ed
nt
lv
e
So
lu
tio
n
0%
So
A.
B.
C.
D.
2. Ionic bonds break up in water
to form a conductive solution
80%
Fa
ls
e
20%
Tr
ue
A. True
B. False
3. Gases follow the same
solubility curve as solids.
A. True
B. False
95%
ls
e
Fa
Tr
ue
5%
4. This is when you change the conditions so
that you can dissolve more of a substance into
the solution than you normally could.
Solution
Solubility
Saturated
Unsaturated
Super saturated
90%
rs
pe
Su
U
at
ur
at
ed
at
ur
at
ed
0%
ns
tu
ra
t
Sa
ili
ty
So
lu
b
n
lu
tio
5%
ed
5%
0%
So
A.
B.
C.
D.
E.
5. This is the substance that is
being dissolved in a solvent.
Solute
Solution
Solubility
Saturated
100%
ed
tu
ra
t
lu
b
So
0%
Sa
ili
ty
0%
n
lu
tio
So
lu
te
0%
So
A.
B.
C.
D.
6. At what temperature is Compound X and Y
equally soluble?
A.
B.
C.
D.
45
170
39
They
are
not.
95%
5%
45
0%
17
0
0%
39
Th
ey
e
ar
t.
no
7. Which compound is considered unsaturated?
60%
Y
40%
X
A. X
B. Y
8. The substance that the solute
is being dissolved in is:
Solution
Solvent
Saturated
Solubility
70%
20%
ili
ty
5%
lu
b
So
Sa
tu
ra
t
ed
nt
lv
e
So
lu
tio
n
5%
So
A.
B.
C.
D.
9.How many grams of compound X is dissolved
at 80 degrees ?
140
70
120
80
95%
0
12
80
5%
0%
70
0
0%
14
A.
B.
C.
D.
10. At what temperature is 80g of compound Y
dissolved?
85%
10%
40
0
0%
10
5%
60
80
60
100
40
80
A.
B.
C.
D.