What does soluble
mean?
Is sugar more
soluble in hot
tea or iced tea?
By experience you know
that sugar will dissolve in
tea.
Sugar is described as
being “soluble” in tea.
Soluble – capable of
dissolving in a particular
solvent.
Back to tea. Why does sugar dissolve faster in hot
tea versus iced tea?
Temperature
•Heating a solvent
allows solvent
molecules to move
faster and their kinetic
energy increases.
•At higher temperatures, collisions between
solvent molecules and the solute are more
frequent and are of higher energy.
•Helps to separate solute particles from each other and
have better dispersion among the solvent molecules.
•Dissolution can be sped
up if surface area of solute is
increased.
•Crushing sugar cubes
increases its surface area.
•The more finely divided a substance is, the greater
the surface area and more quickly it dissolves.
•Stirring or shaking helps to
disperse the solute particles
and bring fresh solvent into
contact with the solute surface.
•Contact between the solute
and solvent is increased.
Is there a limit to the amount of salt that will dissolve in a
glass of water?
Suppose you spoon copper sulfate into water
until no more will dissolve.
There is a little copper sulfate in the bottom.
This means that copper sulfate is dissolving into
the water as fast as copper sulfate is crystallizing
out onto the bottom.
That is dynamic equilibrium.
Solution equilibrium is the physical
state in which the opposing
processes of dissolution and
crystallization of a solute occur at
equal rates.
A solution that contains the maximum amount of
dissolved solute is described as a saturated solution.
A solution that contains less solute than a saturated
solution under the existing conditions is an
unsaturated solution.
A supersaturated solution is a solution that
contains more dissolved solute than a saturated
solution contains under the same conditions.
How does a supersaturated solution form?
Heat
saturated
solution
Let cool
slowly –
unstable
If disturbed –
will rapidly
crystallize
The solubility of a substance is the
amount of that substance required
to form a saturated solution with a
specific amount of solvent at a
specified temperature.
Why does vinegar dissolve in water but
not in vegetable oil?
Type of bonding, polarity or nonpolarity of molecules,
and the intermolecular forces between the solute and
the solvent.
Ionic Compounds
Nonpolar Compounds
Polar Solvents
Nonpolar Solvents
Double, Double, Toil and Trouble…
• What can happen when we mix
liquids together?
Either they mix, or they don’t!
two
• If two liquids mix well together, and one dissolves
in the other, we call them miscible
(think
“mixable”)
• If two liquids do not mix well together, and they
separate, we call them immiscible
(think
“unmixable”)
Like Oil & Water…
• How do we know that two liquids will be
miscible or immiscible?
• Rule of thumb: “Like dissolves Like”
– Polar solutes will dissolve in polar solvents.
– Nonpolar solutes will dissolve in nonpolar
solvents.
• Water is the “universal solvent”.
…And never the two shall meet?
• How can we mix polar and nonpolar
molecules into solutions? Can it be done?
• We use emulsifiers – agents that have both
polar and nonpolar ends to join the two
unlike molecules together.
– Creates an emulsion: A suspension of small
globules of one liquid in a second liquid with
which the first will not mix.
The concentration of a solution is a measure
of the amount of solute in a given amount of
solvent or solution.
Concentration Units
Molarity is the number of
moles of solute in one
liter of solution.
The symbol for molarity is M.
For example, a “one molar” solution of sodium hydroxide, NaOH,
contains one mole of NaOH in every liter of solution.
The concentration of this solution would be written as 1 M NaOH.
amount of solute (mol)
molarity (M) 
volume of solution (L)
Note that a 1 M solution is not made by adding
1 mol of solute to 1 L of solvent.
Molality is the concentration
of a solution expressed in
moles of solute per kilogram
of solvent.
The symbol for molality is m.
For example, a “one molal” solution of sodium hydroxide, NaOH,
contains one mole of NaOH dissolved in exactly 1 kg of solvent.
The concentration of this solution would be written 1 m NaOH.
moles solute
molality 
mass of solvent (kg)