Solution
• a homogeneous mixture
of two or more
components. The
components of a solution
are atoms, ions, or
molecules, which makes
them 10-9 m or smaller in
diameter.
• Ex. Salt water
Suspensions
• The particles in
suspensions are larger
than those found in
solutions. Components of
a suspension can be
evenly distributed by a
mechanical means, like by
shaking the contents, but
the components will
settle out.
• Ex: Oil and Water
Colloids
• Particles intermediate size can be
mixed such that they remain evenly
distributed without settling out. These
particles range in size from 10-8 to 10-6 m
in size.
• The mixture they form is called a
colloidal dispersion.
• A colloidal dispersion consists
of colloids in a dispersing
medium.
• Ex: Milk
Parts of a solution:
1. Solute: substance being
dissolved (NaCl)
2. Solvent: dissolving
medium (H2O)
Solvation: the process of solvent
particles surrounding solute
particles to form a solution
“Like dissolves Like”
This is the general rule to determine
whether solvation occurs.
“Like” refers to the solvent and solute
being either polar or nonpolar.
Polarity of a molecule is a result of how
the electrons are shared and
arranged.
Water is a polar molecule.
“Universal solvent”
Telling Them Apart
• You can tell suspensions from colloids
and solutions because the components of
suspensions will eventually separate.
• Colloids can be distinguished from
solutions using the Tyndall effect.
– A beam of light passing through a true
solution, such as air, is not visible.
– Light passing through a colloidal
dispersion will be reflected by the larger
particles and the light beam will be
visible. (Ex. smoky or foggy air)
When Substances Combine:
1.Soluble: a substance that dissolves
in a solvent
2.Insoluble: a substance that does not
dissolve in a solvent
3.Immiscible: two liquids that are
immiscible, they separate after
mixing (water & oil)
4.Miscible: two liquids that are
soluble in each other.
Rate of Solvation
Factors affecting the rate of solvation:
1. Agitation: stirring, shaking; allows
particles to dissolve faster
2. Temperature: heat adds energy
which allows particles to move
faster and disassociate from each
other faster.
3. Particle size: smaller particles
increase surface area for the solvent
to act on.
Affect of Temperature on
Solubility
Solubility :
maximum
amount of solute
that will dissolve
in a given
amount of
solvent, 100g
usually
Solubility Terminology:
1.Saturated solution: contains the
maximum amount (g) of dissolved
solute
2.Unsaturated solution: contains
LESS than the maximum amount (g)
of dissolved solute
3.Supersaturated solution: contains
MORE that the maximum amount of
dissolved solute.
What type of a
solution is a
solution that
contains 70g
PbNO3 at
40ºC in 100g
H2O?
SATURATED
What type of a
solution is a
solution that
contains 35g
NaCl at
80ºC in 100g
H2O?
UNSATURATED
What type of a
solution is a
solution that
contains
120g K2NO3
at 60ºC in
100g H2O?
SUPERSATURATED
Factors Affecting Solubility:
1.Temperature:
many substances
are more soluble
at high
temperature. But,
gases will dissolve
better at colder
temperatures.
Factors Affecting Solubility:
2. Pressure: Gases
will dissolve best
under pressure.
Henry’s Law:
solubility of a gas
in a liquid is directly
proportional to the
pressure of the gas
above the liquid.
“The BENDS”
Deep sea divers may experience a condition called
the "bends" if they do not readjust slowly to the
lower pressure at the surface. As a result of
breathing compressed air and being subjected to
high pressures caused by water depth, the
amount of nitrogen dissolved in blood and other
tissues increases. If the diver returns to the
surface too rapidly, the nitrogen forms bubbles in
the blood as it becomes less soluble due to a
decrease in pressure. The nitrogen bubbles can
cause great pain and possibly death.
To alleviate this problem somewhat, artificial
breathing mixtures of oxygen and helium are
used. Helium is only one-fifth as soluble in blood
as nitrogen. As a result, there is less dissolved
gas to form bubbles.
Solution Concentrations
Concentration: the amount (g) of
solute dissolved in a specific
amount of solvent
1. Concentrated: large amount of
solute for the amount of solute.
2. Dilute: small amount of solute for
the amount of solution.
Methods of Determining
Concentration of Solution:
Concentration Ratios
Concentration
description
Percent by mass
Percent by volume
Molarity
Ratios
mass of solute
mass of solution x 100
volume of solute
volume of solution x 100
moles of solute
liter of solution
Using Percent to Describe
Concentration
• Percent by mass usually describes
solutions in which a solid is dissolved in
a liquid.
• Represents the ratio of the solute’s
mass to the solution’s mass
expressed as a percent.
• The mass of solution equals the
sum of the masses of the solute and
solvent.
Using Percent to Describe
Concentration
Calculating Percent by Mass
In order to maintain a sodium chloride
concentration similar to ocean water, an
aquarium must contain 3.6 g NaCl per
100g of water. What is the percent by
mass of NaCl in the solution?
Find mass of the solution.
Mass of solution = g solute + g solvent
= 3.6g + 100g
= 103.6 g
Using Percent to Describe
Concentration
Calculating Percent by Mass
In order to maintain a sodium chloride concentration similar
to ocean water, an aquarium must contain 3.6 g NaCl
per 100g of water. What is the percent by mass of
NaCl in the solution?
Substitute values into equation
Percent by mass = mass of solute
mass of solution x100
= 3.6g ÷ 103.6g x 100
=3.5%
Using Percent to Describe
Concentration
Calculating Percent by Volume
• describes solutions in which both the
solute and solvent are liquids
• Volume of the solution is the sum of the
volumes of the solute and solvent
Example: 70% isopropyl alcohol means that
70 volumes of alcohol are dissolved in
100 volumes of water, thus 30 volumes
of water are in every 100 volumes of the
isopropyl alcohol solution.
Using Percent to Describe
Concentration
Calculating Percent by Volume
What is the percent by volume of ethanol in a
solution that contains 35mL of ethanol
dissolved in 155mL of water?
Volume of solution = vol. solute + vol. solvent
= 35mL + 155mL = 190mL
= 35mL x 100
190mL
=18.4%
Calculating Molarity
• Molarity (M) is the number of moles of
solute dissolved per liter of solution.
• Also known as molar concentration.
• A liter of solution containing one mole
of solute is a 1M solution.
• Formula:
Molarity(M) = moles of solute
liters of solution
Calculating Molarity
Example: A 100.5 mL intravenous (IV) solution
contains 5.10g of glucose (C6H12O6). What is
the molarity of this solution? [molar mass of
glucose is 180.16 g/mol]
Use molar mass to calculate the number of
moles of C6H12O6. Round to 4 places after
decimal.
5.10 g C6H12O6 1 mol C6H12O6
180.16 g C6H12O6
= .0283 mol C6H12O6
Calculating Molarity
2. Convert mL to L.
100.5mL x 1L = 0.1005 L solution
1000mL
3. Substitue the known values into the
equation.
Molarity = moles solute
liters of solution
M = 0.0283 mol C6H12O6 = 0.282 mol/L soln.
0.1005 L soln.
= 0.28M
Diluting Solutions
Often stock solutions must be diluted from
one concentration to another. How is the
volume of the stock solution to be diluted
determined?
Rearrange the molarity equation and the
number of moles solute does not change
and we get the equation:
M1V1 = M2V2
Diluting
does
Not add
solute,
Only
solvent.
Diluting Stock Solutions
What volume, in milliliters of 2.00M calcium
chloride solution would you use to make
0.50 L of 0.30M calcium chloride
solution?
Analyze the problem: what do you have
and what are you looking for.
Given
Unknown
M1 = 2.00M CaCl2
V1 = ? L
M2 = 0.300M
V2 = 0.50L
Diluting Stock Solutions
What volume, in milliliters of 2.00M calcium
chloride solution would you use to make
0.50 L if 0.30M calcium chloride
solution?
Solve for the Unknown: rearrange the
equation to solve for the unknown
M1V1 = M2V2
V1 = M2 V2
M1
Diluting Stock Solutions
What volume, in milliliters of 2.00M
calcium chloride solution would you use to
make 0.50 L if 0.30M calcium chloride
solution?
Substitute known values and solve.
V1 = 0.50L x 0.300M
2.00M
V1 = 0.075L x 1000mL
1L
V1 = 75mL
( the question asked for mL!!!)
Colligative Properties
Physical properties of a solution that are
affected by the number of particles in the
solution.
• Lowers vapor pressure: less gas
escapes from the liquid because of the
solute
Colligative Properties
• Raises boiling point: it takes more
energy to overcome the attraction between
the solute and solvent
• Lowers freezing point: solute disrupts
the solvent particles from forming a solid
example: Antifreeze (ethylene glycol)