SOLUTION TERMINOLOGY
1.
A solution is a homogeneous mixture that can exist in
any of the three states – gas liquid or solid.
• Air is a gaseous solution
• Metal alloys are solid state solutions
• Carbonated beverages are liquid solutions of a gas
2.
A solution is composed of:
• the solute: the minor component (least number of moles)
• the solvent: the major component (largest number of moles)
3.
Concentrated / Dilute: A concentrated solution
has a relatively large quantity of a specific solute per
unit amount of solution. A dilute solution has a
relatively small quantity of a specific solute per unit
amount of solution.
GENERAL PROPERTIES OF SOLUTIONS
1. A solution is a homogeneous mixture of two or
more components.
2. It has variable composition.
3. The dissolved solute is molecular or ionic in
size.
4. A solution may be either colored or colorless
nut is generally transparent.
5. The solute remains uniformly distributed
throughout the solution and will not settle out
through time.
6. The solute can be separated from the solvent
by physical methods.
ELECTROLYTES REVIEW
Electrolytes are substances which will conduct electricity
when dissolved in water.
Salts and Strong Acids & Bases form Strong Electrolyte
H20
HCl(s) 
H+
+ Cl-
Salt and strong acids (and bases) are fully dissociated therefore all
of the ions present are available to conduct electricity.
Weak Acids and Weak Bases form Weak Electrolytes
NH3
+
H2O

NH4+
+
OH
Weak electrolytes are partially dissociated therefore not all species
in solution are ions, some of the molecular form is present. Weak
electrolytes have less ions available to conduct electricity.
PROPERTIES OF SOLUTIONS
1. Soluble / Insoluble: A soluble
substance readily dissolves in the
solvent. An insoluble substance will NOT
dissolve readily in a solvent.
2. Miscible / Immiscible: Two liquids are
miscible in each other if they readily mix
to form a uniform solution. Two
immiscible liquids will always separate
out into two distinct layers.
PROPERTIES OF SOLUTIONS
SOLUBILITY - describes the amount of solute that will dissolve in a
solvent. Solubility is also used in a relative way for example, a
substance can be considered either very soluble, moderately
soluble, slightly soluble or insoluble.
- 35.7 of sodium chloride will dissolve in 100g of water at
20oC, so the solubility of NaCl in water is 35.7 g/100g H20
at 20oC
- Polar or ionic substances tend to be more miscible with
other polar substances.
- Nonpolar substances tend to be miscible with other
nonpolar substances.
For example:
1) Sodium Chloride (ionic substance) is soluble in water, slightly
soluble in ethyl alcohol and insoluble in ether and benzene.
2) Pentane, C5H12, a nonpolar substance, is slightly soluble in water
but very soluble in benzene and ether.
PROPERTIES OF SOLUTIONS
Factors which effect solubility:
1. The size of the ions interacting
2. The charge of the ions interacting
3. Attractive and repulsive force interactions
between ions
4. Intermolecular force interactions between
solute and solvent.
5. Temperature
6. Pressure (for gas/liquid solutions)
Factors that Determine
Solubility
Intermolecular Forces: “Like dissolves like”

Factors that Determine Solubility

Temperature: Solubility of most solids increases
with rising temperature. The solubility of gases in
liquids are generally lower at higher temperatures.
Factors that Determine
Solubility

Partial Pressure of a
Solute Gas over Liquid
Solution: “Soda Pop”
General Solubility Rules for aqueous
solutions
Disclaimer: these rules do not address slightly soluble salts.
1. All Na+, K+, and NH4+ salts are soluble.
2. All NO3- and most C2H3O2- are soluble.
3. The Halides are soluble except Ag+, Hg22+, & Pb2+.
4. Sulfates are soluble except Ba2+, Sr2+, and Pb2+.
5. CO32-, PO43-, OH-, & S2- are insoluble except for
those mentioned in #1.
Formation of a Solution
• The dissolving process is reversible. As the dissolved
solute particles move randomly through the solution,
the come into contact with the un-dissolved solute
and crystallize (return to the solid state).
• The rate per unit of surface area at which a solute
dissolves depends primarily on temperature.
• The rate of crystallization per unit area depends
primarily on the concentration of the solute at the
crystal surface.
Formation of a Solution
When the rates of dissolving and crystallization become
the same, the solution is saturated at its solubility at that
temperature and dynamic equilibrium is reached.
When equilibrium is reached, the solution is saturated.
Formation of a Solution
A soluble ionic crystal is placed in water, the negatively charged
ions at the crystals surface are attracted by the positive region of
the polar water molecule. A “tug of war” begins between the
crystal and the water resulting in a hydrated crystal.
FACTORS EFFECTING THE RATE OF
DISSOLVING SOLIDS
1. Particle size: The smaller the particle size, the
more surface area that is exposed thus the easier
the solute dissolves.
2. Temperature: In many cases, temperature
increases the rate of dissolving.
3. Concentration of solution: Dissolving is easier
when there is less solute particles. The rate of
dissolving decreases as the solution nears
saturation.
4. Agitation: Stirring and swirling a solution
increases the kinetic motion thus increases
dissolving.
CuCl2(s)
H2O
Cu+2(aq) + 2 Cl–(aq)
PROPERTIES OF SOLUTIONS
A salt crystal in water
A SATURATED solution occurs
when the rate of dissolving of the
solute (pink dots) into the solvent
(blue dots) is in equilibrium with the
rate of formation of the solute back
into crystalline form. No more
solute can be added without
disturbing the equilibrium, resulting
in the solute “falling” out of solution
and crystal reformation is apparent.
In this picture since the salt crystal
is visible, the solution “saturated”
with the solute. This solution has
the maximum amount of solute
dissolved.
PROPERTIES OF SOLUTIONS
In a SUPERSATURATED solution, the amount of
solute dissolved in the solvent is beyond the
saturated amount. This is possible by altering
some physical conditions in order to “shift” the
equilibrium so more solute can dissolve.
For some substances, an increase in the temperature is one way to
increase how much solute will dissolve in a given solvent. 204 g
of sugar will dissolve in 100 g of water at 20oC but at 50oC you
would be able to dissolve 260 g. If the 50oC saturated solution
was allowed to cool to 20oC and if the sugar remained in
solution then the solution is said to be supersaturated. This is
usually an unstable situation and any disturbance to the cooled
solution could cause the excess solute to “fall out” of solution as
the 20oC saturation equilibrium is established.
PRACTICE PROBLEMS
Short essay: (answers on next slide)
1. Can a saturated solution ever be a dilute solution? Explain.
2. According to the general solubility rules, which one of the following compounds would
be insoluble?
a) NaBr
b) CuS B
c) CaF2
d) (NH4)2S
3. A saturated solution of sodium nitrate contains 80 g NaNO3 per 100 g H2O. How many
grams of NaNO3 must be added to a solution containing 27 g NaNO3 in 65 g H2O to
make the solution saturated?
a) 60 g
b) 35 g
c) 25 g
d) 15 g D
Short essayanswers:
1. Can a saturated solution ever be a dilute solution? Explain.
Yes, a saturated solution can be dilute since the two terms do not
correspond to each other. A saturated solution has the dissolved
solute in equilibrium with undissolved solute, that is, all possible
solute is already dissolved for that given temperature. A dilute
solution contains a small amount of solute relative to the solvent.
An example of a dilute solution that is saturated would be LiF in
water, the solubility of LiF at 0oC is 0.12 g per 100 g of H2O
therfore if you calculate the moles of solute:
0.12 g LiF (1 mol / 25.94 g) = 0.0046 mol of solute
The moles of solvent is: 100 g ( 1 mol / 18 g ) = 5.55 mol of solvent
Upon comparison, since the moles of solvent is 99.9% more than
the moles of solute, one could argue that LiF is dilute relative to
the solvent (Although still saturated).
GROUP STUDY PROBLEMS
Short Essay (write answers on back)
1. Some drinks like tea are consumed either hot or cold but soft drinks are drunk
only cold. Explain.
2. In a saturated solution containing undissolved solute, the solute is continuously
dissolving, but the concentration of the solution remains unchanged. Explain.
___ 3. According to the general solubility rules, which of these salts will not form
a precipitate with lead ion, Pb2+?
a) Br-
b) SO42-
c) CO32-
d) NO3-
e) PO43-
___ 4. A saturated solution of potassium chloride contains 27.6 g KCl per 100 g
H2O. How many grams of KCl must be added to a solution containing 50.0 g
KCl in 235 g H2O to make the solution saturated?