Solubility
Chapter 15.1 B
Vocabulary Word
• Solubility: the maximum amount of solute
that dissolves in a given amount of solvent
at a specific temperature and pressure
Solubility
• Every solute has a characteristic solubility
Solubilities of some solutes in water at various
temperatures
Substance
o
aluminum sulfate
ammonium chloride
barium hydroxide
barium nitrate
calcium hydroxide
lead (II) chloride
lithium sulfate
potassium chloride
potassium sulfate
sodium chloride
0C
31.2
29.4
1.67
4.95
0.189
0.67
36.1
28.0
7.4
35.7
Solubility (g/100 g H2O)
20oC
60oC
36.4
59.2
37.2
55.3
3.89
20.94
9.02
20.4
0.173
0.121
1.00
1.94
34.8
32.6
34.2
45.8
11.1
18.2
35.9
37.1
100oC
89.0
77.3
34.4
0.076
3.20
56.3
24.1
39.2
Solvation
• Particles of solvent
collide with particles
of solute  dissolving
• As more and more
solute dissolves,
some of the dissolved
solute particles collide
with the remaining
crystalline solute 
crystallization
Solvation
• As long as dissolving rate > crystallization
rate more solute will continue to dissolve
(unsaturated solution)
• Eventually dissolving rate = crystallization
rate (dynamic equilibrium: saturated
solution)
Factors Affecting Solubility
• Solubility is how much solute will dissolve
(NOT how fast it dissolves)
– Temperature
– Pressure
Temperature Effects
• Many substances are more soluble at
higher temperature
– More sugar or salt will dissolve in hot liquid
than in cold liquid
Temperature Effects
• Gases are less soluble at higher
temperatures
– As the temperature increases the kinetic
energy increases. This allows gas particles to
escape to the atmosphere
Temperature Effects
Supersaturated Solutions
• Since solubility of some solids increases
with temperature:
– Allows the formation of supersaturated
solutions
– Make a saturated solution at an elevated
temperature
– Cool slowly
Vocabulary Word
• Supersaturated solution: a solution that
contains more dissolved solute than a
saturated solution at the same
temperature.
Supersaturated Solutions
• Are unstable
– Add a seed of solute  crystallization
Supersaturated Solutions
• Are unstable
– Will crystallize on scratches of the container
– Will crystallize if tapped or stirred
Examples of Supersaturated
solutions
• Cloud seeding: silver iodine is spread in
the atmosphere to cause water particles in
supersaturated air to condense and rain to
fall
Examples of Supersaturated
solutions
• Mineral springs have salt crystals along
the edge
Examples of Supersaturated
solutions
• Rock candy is made using a
supersaturated solution of sugar water
Pressure Effects on Solubility
• Solubility of gaseous solutes increase with
increasing pressure (the soft drink won’t
go flat as quickly if the lid is kept on)
Pressure Effects on Solubility
• Soft drinks are carbonated at high
pressure
• When the cap is unscrewed, gas escapes
Spangler Video Clip
• supersaturated solutions:
– http://www.stevespanglerscience.com/experi
ment/00000078
Vocabulary Word
• Henry’s law: the solubility of a gas in a
liquid is proportional to the pressure of the
gas above the liquid
S1
=
S2 solubility at pressure 1
P1
P2 solubility at pressure 2
Henry’s Law
• Is used to determine the solubility at
different pressures