What are some special
properties of solutions?
Chemistry Unit 11
Main Ideas
Mixtures can be either heterogeneous or
homogeneous
Concentration can be expressed in terms of
percent or in terms of moles
Factors such as temperature, pressure, and
polarity affect the formation of solutions
Colligative properties depend on the number
of solute particles in a solution
Types of Mixtures
11.1
Objectives
Compare the properties of suspensions,
colloids, and solutions
Identify types of colloids and types of
solutions.
Describe the electrostatic forces in
colloids
Types of Mixtures
There are heterogeneous and
homogeneous mixtures:
• Heterogeneous Mixtures are a
combination of two or more pure
substances in which each pure
substance retains its individual
properties. There are two main types
of heterogeneous mixtures:
Types of Mixtures
1. Suspensions – A suspension is a mixture
containing particles that settle out if
left undisturbed but, when stirred, the
substance will flow like a liquid.
• These substances are called thixotropic.
These particles can be filtered out.
Example : muddy water
Types of Solutions
2. Colloids – A colloid is made of smaller sizes
of suspension particles and these particles
do not settle out. Particles cannot be
filtered out. The most abundant substance
in a mixture is the dispersion medium.
Example: Milk
• Colloids are categorized according to the
phases of their particles.
Types of Colloids
Colloids
The dispersed particles in a colloid are
prevented from settling out because they
often have polar or charged atomic groups
on their surfaces. This results in the
formation of electrostatic layers around
the particles.
The layers electrostatically repel each
other when the dispersed particles collide,
thus, the particles remain in the colloid.
Colloids
If you interfere with the electrostatic
layering, colloid particles will settle out
of the mixture. Heating also destroys a
colloid because it gives colliding
particles enough kinetic energy to
overcome the electrostatic forces and
settle out.
Brownian Motion
Brownian motion is the jerky, random
movements of particles in a liquid
colloid, from the results of particle
collisions.
Tyndall Effect
Concentrated colloids are often cloudy or
opaque. Dilute colloids sometimes appear
as clear as solutions. Dilute colloids appear
to be homogeneous solutions because their
dispersed particles are so small.
The Tyndall effect is when dispersed colloid
particles scatter light.
Examples: sunlight through smoke filled air
or fog
Homogeneous Mixtures
A homogeneous mixture is a solution of two or
more substances that blend easily and
constant composition throughout. There are
different types of homogeneous solutions:
A solution might exist as a gas, a liquid, or a
solid, depending on the state of its solvent.
Water is the most common liquid solvent.
Examples: salt water and steel
Types of Solutions
Forming Solutions
Some combinations of substances readily form
solutions, and others do not.
A substance that dissolves in a solvent is said
to be soluble in that solvent.
Example: Sugar in water
Two liquids that are soluble in each other are
called miscible.
Forming Solutions
A substance that does not dissolve in a solvent is
said to be insoluble.
Two liquids that cannot be mixed together but
separate shortly after are said to be immiscible
Questions
Miscible substances are:
A. two liquids that are not soluble in
each other
B. solids that dissolve in liquids
C. solids that do not dissolve in
liquids
D. two liquids that are soluble in
each other
Questions
The jerky, random movement of particles
in a liquid colloid is known as ____.
A. Brownian motion
B. Tyndall effect
C. Charles’s Law
D.kinetic energy
Homework
CALM 11.1
p 479 #2, 4, 6,7
Solution Concentration
11.2
Objectives
Describe concentration using different
units
Determine the concentrations of
solutions
Calculate the molarity of a solution.
Expressing
Concentration
Concentration can be expressed in terms
of percent or in terms of moles.
The concentration of a solution is a
measure of how much solute is
dissolved in a specific amount of
solvent or solution.
Expressing
Concentration
Practice Problem #1
In order to maintain a sodium chloride (NaCl)
concentration similar to ocean water, an
aquarium must contain 3.6g NaCl per 100g of
water. What is the percent by mass of NaCl in
the solution?
Answer: 3.5%
Practice Problem #2
120 ml of Sulfuric acid is mixed with 340
ml of water. What is the percent by
volume of acid in the solution?
Molality
Molality is the ratio of moles of solute
dissolved in 1 kg of solvent.
Practice Problem #3
In the lab, a student adds 4.5g of sodium
chloride (NaCl) to 100.0g of water.
Calculate the molality of the solution.
0.77 mol/kg
Mole Fraction
Mole fraction is the ratio of the number
of moles of solute in solution to the
total number of moles of solute and
solvent.
where XA and XB represent mole fractions
of each substance
Practice Problem #4
100 g of a hydrochloric acid solution
contains 36 g of HCl and 64 g of H2O.
What are the mole fractions of HCl and
water?
.22 HCl
.78 H2O
Molarity
Molarity is the number of moles of solute
dissolved per liter of solution.
Dilution equation: M1V1 = M2V2
Practice Problem #5
A 100.5 ml intravenous (IV) solution contains
5.10 g of glucose (C6H12O6). What is the
molarity of this solution?
Ans: 0.282M
Practice Problem #6
If you needed to make a 1.0 M solution of
CaCl2, how many grams would you need
to make 500 ml of it?
5.5g
Practice Problem#7:
Dilution
What volume of 2.00 M calcium chloride
stock solution would you use to make
0.50 L of 0.300 M calcium chloride
solution?
75 ml or .075L
Question
Which is NOT a quantitative measure of
concentration?
A. molarity
B. molality
C. percent by mass
D.dilute
Question
The number of moles of solute divided by
liters of solvution is called ____.
A. molarity
B. molality
C. percent by volume
D.percent by mass
Homework
CALM 11.2
p481-483 #9,10, 16-18
p485-487 # 20-22, 24, 25, 27, 29
Factors Affecting
Solvation
11.3
Objectives
Describe how intermolecular forces
affect solvation.
Define solubility.
Understand what factors affect
solubility.
Solvation
The process of surrounding solute particles
with solvent particles to form a solution is
called solvation.
Solvation in water is called hydration.
“like dissolves like”
Solvation
Factors that Affect
Solvation
Agitation – shaken or stirred – agitation
of the mixture allows for more contact
between solute and solvent.
Surface area – breaking the solute into
small pieces helps solvation. A greater
surface area allows more collisions to
occur.
Factors that Affect
Solvation
Temperature – As temperature
increases, the rate of solvation also
increases. Additionally, hotter solvents
generally can dissolve more solid
solute.
Solubility
Solubility is the ability of a solvent to
dissolve a solute.
In an aqueous solution, a precipitate
forms when a mixture produces an
insoluble product.
Solubility Guidelines
1. All common salts of the group 1 elements
and ammonium ions are soluble.
2. All common acetates and nitrates are
soluble.
3. All binary compounds of group 17 elements
(other than F) with metals are soluble
except hoes of silver, mercury (I), and lead.
Solubility Guidelines
4. All sulfates are soluble except those of
barium, strontium, lead, calcium, silver, and
mercury (I).
5. Except for those in Rule 1, carbonates,
hydroxides, oxides, sulfides, and
phosphates are insoluble.
Practice Problem #8
Which of the following substances would be
a precipitate in an aqueous solution? Why?
a) NaCl
b) CaCO3
c) Fe(NO3)
d) KOH
Solubility
Unsaturated solutions – An unsaturated
solution is one that contains less
dissolved solute than the solvent can
handle at a certain temperature and
pressure.
In other words, more solute can be
dissolved in an unsaturated solution.
Solubility
Saturated solution – The maximum
amount of solute has been dissolved in
the solvent. The amount of
crystallization is at equilibrium with the
amount of solvation.
In other words: The solution cannot
dissolve anymore solute.
Solubilty
A supersaturated solution contains more
dissolved solute than a saturated solution at
the same temperature and are considered
unstable.
To make a supersaturated solution, a saturated
solution is formed at a high temperature and
then cooled slowly.
The slow cooling allows the excess solute to
remain dissolved in solution at the lower
temperature.
Solubility of Gases
Gases, in general, are less soluble at
higher temperatures than at lower
temperatures. At higher temperatures,
the gases have a higher kinetic energy
that allows them to escape from a
solution.
Henry’s Law
Pressure affects the solubility of gaseous
solutes in solutions. The solubility of a gas in
any solvent increases as its external pressure
increases.
Carbonated beverages rely on the container
to provide enough pressure to keep gas
dissolved in the solution.
Henry’s Law
Henry’s law states that at a given
temperature, the solubility (S) of a gas
in a liquid is directly proportional to the
pressure (P) of the gas.
S1 S2
=
P1 P2
Practice Problem #9
If 0.85 g of a gas at 4.0 atm of pressure
dissolves in 1.0 L of water at 25°C, how
much will dissolve in 1.0 L of water at 1.0
atm of pressure and the same
temperature?
.21 g/ liter
Question
For a given amount, which type of
solution contains the LEAST amount of
solute?
A. solvated
B. saturated
C. supersaturated
D.unsaturated
Question
At a given temperature, the solubility of a
gas is directly proportional to what?
A. volume
B. mass
C. molarity
D.pressure
Homework
CALM 11.3
p497 #36, 37, 39, 41
Solution Stoichiometry
11.4
Objectives
Solve solution stoichiometry problems
and solution limiting reactant problems.
Determine excess concentration of ions
after a reaction.
Solution Stoichiometry
Stoichiometry applies to solutions too.
The number of moles of a reactant
and/or product can be found with
concentration using the concentration
equations.
Most solution stoichiometry utilizes the
net ionic equation.
Solution Stoichiometry
Concentration of ions can be found in a
solution by using the ratios in a
compound.
For example: 1.0 M CaCl2 has 1.0 mole
of Calcium (Ca2+) in 1 liter of solution
and 2.0 moles of chloride (Cl-)
Practice Problem #10
What is the concentration of sodium ions
in 1 liter of a 2.0 M solution of sodium
sulfate?
4.0 M
Practice Problem #11
What mass of solid aluminum hydroxide
can be produced when 50.0ml of 0.200
M Al(NO3)3 is added to 200.0 ml of 0.100
M KOH?
Practice Problem #12
A 100.0 ml of 0.200 M aqueous potassium
hydroxide is mixed with 100.0 ml of 0.200 M
aqueous magnesium nitrate. Write a
balanced equation and net ionic equation.
What mass of precipitate is produced and
what is the concentration of each ion
remaining in solution after the reaction is
complete.
Practice Problem #13
What mass of silver chloride can be prepared
by the reaction of 100.0ml of 0.20 M silver
nitrate with 100.0 ml of 0.15 M calcium
chloride? Write the balanced equation and
net ionic equation. Calculate the
concentration of each ion remaining in
solution after precipitation is complete.
Accumulating Content
11.5
Accumulating Content
How does the net ionic change the way
stoichiometry is calculated? What are the
pros and cons?
Accumulating Content
How does concentration affect solutions?
Accumulating Content
How is solvation similar to ionic compounds?
Key Concepts
The individual substances in a
heterogeneous mixture remain distinct.
Two types of heterogeneous mixtures are
suspensions and colloids.
Brownian motion is the erratic movement
of colloid particles.
Colloids exhibit the Tyndall effect.
Key Concepts
A solution can exist as a gas, a liquid, or a
solid, depending on the solvent.
Solutes in a solution can be gases,
liquids,
or solids.
Concentrations can be measured
qualitatively and quantitatively.
Key Concepts
Molarity is the number of moles of solute
dissolved per liter of solution.
Molality is the ratio of the number of
moles of solute dissolved in 1 kg of solvent.
Key Concepts
The number of moles of solute does not
change during a dilution.
M1V1 = M2V2
The process of solvation involves solute
particles surrounded by solvent
particles.
Key Concepts
Solutions can be unsaturated, saturated,
or supersaturated.
Henry’s law states that at a given
temperature, the solubility (S) of a gas in
a liquid is directly proportional to the
pressure (P) of the gas above the liquid.
The END