Use the side
to list main
points
Organize
ideas (if you
get bored
do this in
class!)
Ask
questions
such as
might be on a
test or that
you wonder
about
Use thinking
skills to
question,
bring ideas
together,
and extend
them
CORNELL NOTES
In the body of the notes:
Take notes in class in the format that is most
comfortable to you:
Outline, text, shorthand, sketches, diagrams,
examples
Do NOT copy notes word for word
think as you write
rephrase
abbreviate
organize
At the bottom, summarize main ideas at appropriate intervals
SOLUTIONS
A solution is a homogeneous mixture; particles are evenly
distributed throughout the mixture.
Proportions may vary
• Uniform ratio throughout the mixture
•
A liquid solution is clear. The particles are not visible, do not settle,
and can not be filtered.
A solution differs from a suspension in that the particles of a
suspension are visible, can be filtered, and settle.
A solution differs from a colloid in that the particles of a colloid
exhibit Tyndall effect., yet do not settle.
(TYNDALL effect: the scattering of light by particles such as
headlights in fog, flashlight through Jello or dilute milk)
A solution will not exhibit the Tyndall effect.
SOLUTIONS Solns
homogeneous mixture
evenly distributed particles
•
variable proportions
•
uniform ratio
liquid soln clear. particles are not visible, do not settle, and can
not be filtered.

Not suspensions: particles of a susp are visible,
can be filtered, and settle.

Not colloids: particles of a colld exhibit Tyndall effect,
yet do not settle.

(TYNDALL effect: the scattering of light by particles
such as headlights in fog, flashlight thru dilute milk)

A solution will not exhibit the Tyndall effect.
SOLUTIONS Solns
Define
soln
Describe
soln
Are all
solns
liquid?
homogeneous mixture
evenly distributed particles
•
variable proportions
•
uniform ratio
liquid soln clear. particles are not visible, do not settle, and can
not be filtered.

Not suspensions: particles of a susp are visible,
can be filtered, and settle.
Contrast
liquid
soln with
susp and
colloids

Not colloids: particles of a colld exhibit Tyndall effect,
yet do not settle.

(TYNDALL effect: the scattering of light by particles
such as headlights in fog, flashlight thru dilute milk)

A solution will not exhibit the Tyndall effect.
SOLUTIONS Solns
Define
soln
Describe
soln
Are all
solns
liquid?
Contrast
liquid
soln with
susp and
colloids
homogeneous mixture
evenly distributed particles
•
variable proportions
•
uniform ratio
liquid soln clear. particles are not visible, do not settle, and can
not be filtered.

Not suspensions: particles of a susp are visible,
can be filtered, and settle.

Not colloids: particles of a colld exhibit Tyndall effect,
yet do not settle.

(TYNDALL effect: the scattering of light by particles
such as headlights in fog, flashlight thru dilute milk)

A soln will not exhibit the Tyndall effect.
Solutions are homogenous mixtures with variable proportions and
uniform ratios. Separate components are not visible/discernible.
Cherry Kool-aid
Red powder: flavor and color
 White crystals: sugar
 Clear liquid: water


One substance dissolved in another
◦ Solute: the substance being dissolved
◦ Solvent: the substance that dissolves the
solute
 Sugar is the SOLUTE (smaller quantity)
 Water is the SOLVENT (larger quantity)
Types of Solutions

Gas (solvent is gas)
◦ Gas into Gas: air
◦ Liquid into Gas: humidity
◦ Solid into Gas: air pollution

Liquid (solvent is liquid)
◦ Gas into Liquid: pop
◦ Liquid into Liquid: vinegar
◦ Solid into Liquid: sweet tea

Solid (solvent is solid)
◦ Gas into Solid: absorbent charcoal
◦ Liquid into Solid: dental fillings
◦ Solid into Solid: alloys of metal
The Dissolving Process

Two factors affect the dissolving process:
dissolution
◦ The constant motion of the particles (There’s
that good old kinetic molecular theory again!)
◦ The polarity of the solute and solvent (Recall
that polarity is when a compound has partial
charges because of uneven distribution of
charges)
Steps of the Dissolving Process
Moving solvent particles cluster around
solute molecules or particles at the
surface of the solid.
2. Solvent molecules pull solute off of the
solid surface and into solution.
3. Moving solvent particles continue to
spread solute evenly throughout the
solution,
The process repeats itself as fresh layers of
the solute are exposed.
1.
1. Solvent particles cluster around solute particles at the
surface.
2. Solvent particles pull solute particles away from
surface, into solution.
3. Moving solute particles continue to spread solute
evenly through solution.
MOLECULAR
1. Solvent particles cluster around solute particles at the
surface.
2. Solvent particles pull solute particles away from
surface, into solution.
3. Moving solute particles continue to spread solute
evenly through solution.
IONIC
IONIC COMPOUNDS
When an ionic substance dissolves in water, the
forces of the solvent pulling on the ions is
stronger than the forces holding the ions
together.
 The ions separate. This is called
DISSOCIATION
 Because charged ions are present in an ionic
solution, ionic solutions conduct electricity and
are called ELECTROLYTES.
 EXAMPLE: NaCl

MOLECULAR COMPOUNDS
Certain polar substances form ions when
they dissolve in water.This process is
called IONIZATION.
 Because ions are formed, the solution
conducts electricity.
 These substance are also
ELECTROLYTES.
 EXAMPLE: HCl, HC2H3O2

MOLECULAR COMPOUNDS
Other polar substances do not ionize in
water.
 Because ions are not formed, the solution
does not conduct electricity.
 These substances that do not ionize in
water and do not conduct electricity are
called NON-ELECTROLYTES.
 EXAMPLE: sugar

ELECTROLYTES:
substances that conduct
electricity when dissolved in water
Ionic substances that separate into ions
(dissociate) or polar molecular substances
that form ions (ionization) when dissolved
conduct electricity and are called
ELECTROLYTES.
 Molecular substances that do not ionize
when dissolved do not conduct electricity
and are called NONELECTROLYTES.

NONELECTROLYTES
Molecular substances that do not ionize when dissolved do not
conduct electricity and are called NONELECTROLYTES.
SOLUTIONS
NONELECTROLYTES
Do not conduct
electricity
ELECTROLYTES
Conduct electricity
IONIC COMPOUNDS
DISSOCIATE
into ions
SOME POLAR
MOLECULAR
COMPOUNDS
IONIZE
to form ions
OTHER POLAR
MOLECULAR
COMPOUNDS
DO NOT IONIZE
Review

A substance that separates into ions
(dissociates) or forms ions (ionizes) in a
water solution conducts electricity and is
called an electrolyte
◦ All ionic and some molecular/covalent
compounds

A substance whose water solutions do
not conduct electricity is a nonelectrolyte.
◦ Many molecular/covalent compounds
What factors affect the rate of
dissolution?
The experiment
provides a model;
it demonstrates
some ideas well
but is not entirely
accurate!
FACTORS THAT AFFECT THE RATE OF DISSOLUTION
Factors
TEMPERATURE
Solid in Liquid
Gas in Liquid
Temp >
Rate >
Temp >
Rate <
AGITATION
Agitation >
Rate >
Agitation >
Rate <
SIZE OF
PARTICLES
Size <
(surface area >)
Rate >
NA
PRESSURE
NA
Pressure >
Rate >
The solute
particles are less
energetic than
solvent
The solute
particles are
more energetic
than solvent
WHY?
Think BIG
Recall the Pop and Mentos experiment!
The pop “explodes” because the dissolved gas rapidly
leaves the solution because the candy gives it surfaces
to collect on (nucleation sites).
Particles in Solutions

Solvents with non-polar molecules
dissolve non-polar substances
◦ Oil, grease, dry cleaning fluid, paint, turpentine

Solvents with polar molecules dissolve
polar substances
◦ Water dissolves sugar, ionic compounds

LIKE DISSOLVES LIKE
Terms
Soluble: capable of being dissolved in a
particular solvent
 Insoluble: incapable of being dissolved in a
particular solvent

Miscible: liquids that dissolve freely in any
proportion
 Immiscible: liquids that are not soluble in
each other

Detergents and emulsifiers
Grease is non-polar
 Water is polar


DETERGENT has
◦ A non-polar end that dissolves the grease
◦ A polar end that dissolves in the water to
rinse it away
NONPOLAR
GREASE
DETERGENT
POLAR
WATER
What does “like dissolves like” mean?
This experiment
demonstrates “like
dissolves like”
Use your
observations and
knowledge of soap
to explain this.
Solubility
There are limits to the amount of solute
that will dissolve in a given amount of
solvent at a given temperature
 There are some general terms:

◦ Unsaturated
◦ Saturated
◦ Super-saturated
Unsaturated

a solution that can dissolve more of a
given solute at a certain temperature
◦ A crystal of solute added to an unsaturated
solution will dissolve
 When you add a second spoon of sugar to your
cup of tea, it dissolves. The tea was an unsaturated
solution.
Saturated

a solution that has dissolved all of the solute
that it can at a certain temperature
◦ A crystal of solute added to a saturated solution will
drop to the bottom, un-dissolved.
 When you add three spoons of sugar to your tea, some sugar
drops to the bottom, undissolved. It is a saturated solution.

DYNAMIC EQUILIBRIUM exists:
◦ changing but balanced.
◦ Some solid dissolves, but as some dissolves, some recrystallizes
Super-saturated

an unstable solution that contains more solute
than a saturated solution at a certain
temperature
◦ A crystal of solute added to a super-saturated
solution will cause crystallization. So will any
disruption of the unstable solution.
◦ Make a saturated solution at an elevated temperature
and cool it slowly. At the lower temperature, the
solute will remain dissolved in an unstable situation. If
disrupted, the solute crystallizes.
 Hot-packs and rock candy
S
O
L
U
B
I
L
I
T
Y
C
U
R
V
E
Max g of solute that will
dissolve in 100 g of
solvent at a given
temperature
Exothermic and Endothermic

Exothermic: Some substances release
heat when they dissolve and feel warm.
◦ Hand-warmers

Endothermic: Some substances absorb
heat when they dissolve and feel cold.
◦ Cold-packs
Concentration: the amount of solute in
a given amount of solvent or solution
Dilute: a relatively small amount of solute
in a relatively large amount of solvent
 Concentrated: a relatively large amount of
solute in a relatively small amount of
solvent


We can do better!
PPM and PPB
x/1,000,000
 x/1,000,000,000


Serial dilutions are often used
◦ 1x, 10x, 100x, 1000x, etc.
Often used in environmental studies of water
and air. Contaminants may be significant in the
PPB range!
Percent by volume

mL of solute /100 mL of solution
30% rubbing alcohol
30mL isopropanol/100mL of solution x 100% =
30% v/v isopropyl alcohol
(v/v means volume to volume)
The solvent is usually the substance present in greater
quantity.
Percent by mass
g of solute/100 mL of solution
 Often used in medicine…

◦ 5% glucose or .9% saline are two examples
.9% saline solution
.9 g salt/100 mL solution x 100% =
.9 % m/v solution of saline
(m/v means mass to volume)
Mass per volume

g solute/1000 mL solution
40 g NaOH/1000 mL solution
This is not really very helpful, but you can
figure out how much NaOH is in a
certain volume:
20. mL x 40. g/1000 mL = .80 g NaOH
Molarity

M = mol solute/liter of solution

Chemists use this because it lets us work
concentration into stoichiometry
problems
40 g NaOH x
1 L soln
1 mol NaOH
40 g NaOH
= 1 M NaOH = 1 mol NaOH
1 L soln
Molality…one letter difference!

m = mol solute/kg of solvent
40 g NaOH x
1 kg solvent

1 mol NaOH
40 g NaOH
= 1 m NaOH = 1 mol NaOH
1 kg solvent
Chemists sometimes use this because
volume of liquids changes with
temperature. Soon, we will be studying
the effect of concentration on properties
as temperature changes.
Dilutions: a concentrated solution is diluted by adding
more solvent to get the desired concentration.

M1V1
 Moles before dilution
◦ M = molarity = mol/L
◦ V = volume = L
=
=
M2V2
Moles after dilution
◦ M x V = mol/L x L = # mol of solute

The # of moles before dilution is equal to the # of
moles after dilution. The same # of moles is present in
more solvent. The concentration (M, molarity) changes,
the volume (V) changes, but not the # of moles of
solute (M x V).
◦ Volume units may vary from L, but must be consistent within problem.

So, M1V1 = M2V2
M 1V 1 = M 2 V 2

How do you prepare 100 mL of 0.40 M NaCl
from a stock of 2.0 M NaCl?
M1V1
=
M2V2
2.0 M ( x )
=
0.40 M (100 mL)
x
=
20 mL
Measure 20. mL of stock and dilute to a total
volume of 100 mL in a “volumetric flask.”
Note: volume can be any units, but must be consistent.