Chapter 12-13:
Mixtures and Aqueous
Solutions
We use solutions
all the time
What are they?
Where do we find them?
How do we describe them?
Soluble versus insoluble
• Some solids are soluble in water, ie: table salt,
NaCl. Soluble means: able to be dissolved.
• Soluble ionic solids (made of cation and anion)
dissociate into their ions in water.
• Soluble covalent solids (like sugar) dissolve
because they are relatively polar.
Back
• In a solution, the dissolved particles cannot be
easily seen or separated from the solution.
• Alloys are solutions of metals!
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Slide 3
Parts of a solution
• The dissolving medium is the solvent
(what does the dissolving)
• The dissolved substance is the solute
(what gets dissolved)
• The solute and solvent together form the
solution.
• Solvents and solutes can be any phase.
solution
Special types of mixtures - Suspensions
• Suspensions
– mixtures where the solutes particles
are very large, so they don’t
completely dissolve into their solvent.
• Solute particles will settle out of
the solution if left undisturbed. –
this creates two phases.
• Muddy water and Italian salad
dressing are good examples of
suspensions.
Special types of mixtures - Colloids
• Colloids
– mixtures where the solute particle is smaller than
particles in a suspension, but not small enough to
dissolve.
• Colloids have two phases:
Dispersed phase – the solute
Dispersing medium – the solvent.
Colloids
Back
• Mayonnaise and hair gel are good examples of
colloids.
• There are 7 types of colloids, found on page
404…
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Slide 7
Page 404
Colloid Type
7 Types of Colloids
Phases
Example
Sol
solid in liquid, liquid substance
Paint
Gel
solid in liquid, solid substance
Gelatin
Foam
gas in liquid
Whipped cream
Liquid
Emulsion
liquid in liquid
Milk, mayonnaise
Solid Emulsion
liquid in solid
Cheese, butter
Solid Aerosol
solid in gas
Smoke
Liquid Aerosol
liquid in gas
Clouds, fog
Two groups of colloids:
Heterogeneous colloids – two phases are clearly seen
Homogeneous colloids – appears to be one phase
The Tyndall Effect
John Tyndall,
Brittish, c1860
The Tyndall effect allows us to distinguish
between solutions, colloids, and suspensions.
It works by shining a beam of light into the
mixture. If…
Results of Tyndall Effect
Back
• Light doesn’t pass through
– the mixture is a suspension or a heterogeneous
colloid.
• Light passes through unobstructed
– the mixture is a solution.
• Light passes, but the beam can be seen in the
mixture
– the mixture is a homogeneous colloid
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Slide 10
The Tyndall Effect
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Back
Slide 11
Electrolytes
• Electrolytes
– Solutions that conduct electricity.
• Ionic solutions are electrolytes.
• Covalent solutions are nonelectrolytes.
What do you think?
Back
Is saltwater (NaCl in water) an electrolyte?
Is sugar water (C6H12O6 in water) an electrolyte?
Conductivity tester (meter)
– can tell us if a solution is an electrolyte, and
sometimes, how strong an electrolyte is.
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Slide 13
• Solubility
Solubility
– The extent to which a solute will dissolve in a
solvent. (how much solute will dissolve)
• High solubility
– large amounts of solute will dissolve in a solvent
• Low solubility
– only small amounts of solute will dissolve
Warm Up
Back
I am collecting:
Thermo Article Analysis (get it to me by
Monday if it isn’t done!)
Book Notes- 16.1 and 10.4
Thermo Review
Last minute questions?
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Slide 15
Solubility
Back
• Increasing temperature increases the solubility
of solids in liquids.
• Increasing temperature decreases the solubility
of gases in liquids! …
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Slide 16
Reading Solubility Curves
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Back
Slide 17
Solid-Liquid solubility with temperature
Back
Gas-Liquid solubility with temperature
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Slide 19
Gases in liquids
• In addition to cold
temperatures, high
pressures increase
solubility of gases in
liquids.
• Henry’s Law:
– solubility of a gas in
a liquid increases
with increasing
pressure of that gas
above the liquid.
Like Dissolves Like!
• Some solvents are polar, having partial negative and
partial positive ends. (H2O)
• Other solvents are nonpolar, having no “+” “-” poles
• Polar solutes tend to dissolve well in polar solvents…
• Nonpolar solutes tend to dissolve well into nonpolar
solvents.
Like Dissolves Like
Back
Water is very polar. Does it dissolve polar
substances or non polar substance?
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Slide 22
Saturation
• Saturated Solution
– solution has as much solute in it as it will allow
(equal to solubility)
• Unsaturated Solution
– more solute can still dissolve into solution (less than
solubility)
• Supersaturated Solution
– too much solute in solution-some will fall out (more
than solubility)
• We express the quantitative amount of solute
in a solution with concentration …
Solid-Liquid solubility with temperature
Warm UP
Back
1. Which solute is more
soluble at 30C?
2. What is the solubility of
KCl at 80 C?
3. How much would you
add to 20g of KCl in
200g of water to
saturate the solution?
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Slide 25
What is the general rule for
determining solubility?
Solvents
Water
CCl4
Back
Solutes
I2
NaCl
KNO3
Br2
Benzene
C2H6O- ethanol
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Slide 26
Which would be electrolytes when
dissolved in water?
Back
I2
NaCl
KNO3
Br2
Benzene
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Slide 27
How did you do on the HW?
Back
Get into your small groups and compare answers!
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Slide 28
Solubility of KNO3 Lab
Back
1. Number your test tubes 1 – 4.
2. Mass 2.0g, 4.0g, 6.0g and 8.0g into the test
tubes… the actual amt doesn’t matter as long
as you record the values.
3. Place 5 ml of distilled water into your test
tubes.
4. Heat them all up…and wait for them to
dissolve.
5. Record the temperature where you see the
crystals reforming (saturation point).
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Slide 29
Back
Warm Up- Use your Solubility Curve WS to answer the
questions on the half sheet!
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Slide 30
Back
Would the following be soluble in
water? Would they be electrolytes?
Hexane- C6H14
MgCl2
NaOH
CO2
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Slide 31
Demo
Back
Classify the following as a solution, colloid or
suspension.
1. NaCl in water?
2.
3.
4.
5.
Clay (a compound with Si, C and H)
Na2CO3
Sugar in water (C6H12O6)
Corn Starch (a hydrocarbon) in water
Electrolyte or nonelectrolyte?
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Concentration - Molarity
• The “Stoichiometry” of Solutions
• Concentration
– the quantitative amount of solute present in a
solution
• Molarity (M) – moles/liter
– number of moles solute in liters of solution
amount of solute (mol )
Molarity ( M ) 
volume of solution ( L)
Try these Molarity questions
• What is the concentration [in Molarity] when 3 moles
of NaCl are dissolved in 2 Liters of water?
1.5 M
“molar”
• How much (in liters) of a 0.1 M solution do you need
to get 2 moles of solute?
20 L
• How many moles of NaOH are present in 300mL of a
1M solution?
.3 moles
• How many grams of HCl are found in 100mL of a 2M
solution?
7.2 grams
Back
Work on the 1st 3 problems- Front and Back…
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Slide 35
Warm Up
Back
Are the following substances soluble in water?
Chlorine- Cl2
CF3I
NaCO3
Would they be electrolytes or nonelectrolytes?
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Slide 36
Questions on Molarity Packet?
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Back
Slide 37
Back
Are all Ionic Compounds Soluble?
Let’s look at the solubility rules…
These are very important when looking at what
happens in double replacement reactions.
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Slide 38
Solubility Lab
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Back
Slide 39
Back
Warm Up: Predict the products, balance the
equation and determine the states of matter
NaCl + CaNO3
LiSO4 + SrCl2
BaCl2 + H2S
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Slide 40
Solubility Rule Lab
Back
Questions on the lab??
Did you…
Write the first 30 equations and indicate the
states of matter?
Identify ALL the precipitates?
Answer the questions using complete
sentences?
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Slide 41
Dissociation and Ions Present
• Dissociation = a salt dissolving into its ions:
NaCl( s )  Na

( aq)
 Cl

( aq)
• How many moles of ions are in a solution of 1
mole of NaCl?
• How many moles of ions are in solutions of 1
mole of each of the following?:
2
CuSO4  Cu  SO4
2
Mg ( NO3 ) 2  Mg
2

 2 NO3
Na2CO3  2 Na  CO3

2
Net Ionic Equations
• When we write a balanced chemical equation,
we show all species present (all reactants and
all products):
AgNO3( aq)  NaCl( aq)  AgCl( s )  NaNO3( aq)
• In a net ionic equation, we show only
precipitates formed, and the reactants that
form them:


Remember to Balance
Ag
( aq)
 Cl
( aq)
 AgCl( s )
• The chemicals that stay ions are called
spectator ions, And are left out (Na+, NO3-)
Net Ionic Equation Practice
• Write the net ionic equations for the following:
Pb( NO3 )2( aq)  KI( aq)  (double displacement )
Pb2 ( aq)  I  ( aq)  PbI 2( s )
Net Ionic Equation Practice
Back
• Write the net ionic equations for the following:
NiCl2( aq)  K2 S( aq)  (double displacement )
Ni
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2
( aq)
S
2
( aq)
 NiS ( s )
Slide 45
Net Ionic Equation Practice
Back
• Write the net ionic equations for the following:
BaCl2( aq)  Na2CO3( aq)  (double displacement )
Ba
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2
( aq )
 CO3
2
( aq )
 BaCO3( s )
Slide 46
Now you are ready to work on the
homework WS…
Back
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Slide 47
Strong/Weak Electrolytes
• Recall that a solid compound made up of a
cation and anion is called a salt.
• Salts that dissolve completely into their ions
when put in water dissociate completely.
• Salts that dissociate completely form strong
electrolytes – solutions that conduct electricity
well.
• Some salts only partially dissociate, forming
weak electrolytes – solutions that conduct
electricity, but do so poorly.
Quiz…
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Back
Slide 49
Solution Preparation
By solid dissolving:
1. Calculate how many grams are needed to create our
volume of our desired molarity solution
2. Weigh out that mass, and add it to a volumetric flask
3. add some water and allow to dissolve
4. add water to the desired volume
Back
Let’s make 1.0L of a 2.0M NaCl solution.
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Slide 51
Try these!!
Back
How many grams of sodium chloride are needed
to make a 1.3M solution?
How much sodium hydroxide is needed to make
a 4.6M solution?
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Slide 52
Solution Preparation
Back
By dilution of a standard solution:
1. Use the relationship M1V1=M2V2
2. Calculate volume of the “standard
solution” to use to get desired volume
of desired molarity solution.
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Slide 53
Back
Try these…
1. How much 12 M stock solution is needed to
make 500.mL of a 3.5M solution?
2. What is the molarity of a stock solution where
you used 200. ml to make 0.5 L of a 2.5M HCl
solution.
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Slide 54
Solution Formation
Back
• The nature of the solvent and solute affects
whether a substance will dissolve
• Other factors determine how fast a soluble
substance dissolves
– Agitation (shaking)
– Temperature
– Solute particle size
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Slide 55