Solutions
13.1: The Nature of Solutions
1. Solution: A homogeneous mixture of 2 or
more substances in a single physical state
(visibly the same throughout.)
A. Properties of Solutions:
1. small particles
2. particles are evenly distributed
3. particles won’t separate when allowed to
stand
4. every substance has it’s own solubility
B. Vocabulary:
1. Solute: substance that is dissolved
(usually  50% of solution)
solvent
solute
2. Solvent: substance that does the dissolving
(usually  50% of the solution)
3. Soluble: something can be dissolved in a solvent.
Ex) salt in H2O
4. Insoluble: something cannot be dissolved in a
solvent.
Ex) iodine in water
C.Types of Solutions:
1. Solid Solutions (solid solvent)
Alloys: solid solution that contains two or more
metals.
Ex) steel – 99% Fe & 1% C, gold jewelry, brass
Advantages of alloys over pure metals: stronger,
corrosion resistant, cheaper, attractive color
2. Gaseous Solutions: (gaseous solvent)
The properties of gaseous solutions depend
on the properties of its compounds. Ex) air
3. Liquid Solutions: (liquid solvent)
Miscible liquids: Two liquids that are able to
mix together in any proportion.
Ex) alcohol & water
Immiscible liquids: Two liquids that are
unable to mix together in any proportion.
Ex) oil & water (lava lamps)
Aqueous Solutions:
Solutions with H2O as
the solvent. Because
water can dissolve so
many things, it is called
the universal solvent.
Tincture: Solutions with
alcohol as the solvent.
Ex) iodine & alcohol
Electrolyte: ionic compounds dissolve in water
to form ions that can conduct an electric
current. Ex) salt & water
Nonelectrolyte
Electrolyte
Nonelectrolyte: molecular (covalent)
compounds dissolve in water to form
molecules that cannot conduct an electric
current. Ex) sugar & water
D. Separating Solutions: Done through a change
of state - evaporation or condensation.
(distillation)
Type of Solution
Gas in Gas
Air
Specific Solute IN Specific Solvent
O2
N2
CO2
H2O
hydrocarbons
Pt
H2O
air
lemon juice
water
mercury
silver
carbon
air
sugar
water
carbon
iron
Gas in Liquid
Soda
Gas in Solid
catalytic converter
Liquid in Gas
fog
Liquid in Liquid
Lemonade
Liquid in Solid
teeth fillings
Solid in Gas
smoke
Solid in Liquid
Kool-Aid
Solid in Solid
steel
Solution Concentration
During the past 50 years, the detection limit of contaminants present in air or water samples has
become very small; in some cases special instruments can detect just a few molecules!
• pph
• ppt
• ppm
• ppb
• pptr
1 penny in $10,000
1 minute in 2 years
1 dime in a mile-high stack of pennies
1 penny in $10,000,000
1 pinch of salt in 10 tons of potato chips
1 second in 32 years
1 penny in $10,000,000,000
1 second in 320,000 years
EPA Action Level for Lead
• 15 ppb (some studies have shown as low as 5 ppb
concentration to be a problem.)
• Some homes in Flint, Michigan are between
4,000 – 12,000 ppb (4-12 ppm!)
• Lead poisoning causes: irritability, lack of
coordination, memory lapses, lethargy, headaches
and lower IQ scores in children.
Which is more sensitive? eyes or nose?
*eyes can detect down to about 1 ppm
*nose can detect down to about 10 ppb (organics like TCE)
13.2: Concentrations of Solutions
A. Terms Used for Concentration: The amount of
solute in a given amount of solvent or solution.
Relative
1. Concentrated: When a solution has a large
terms –
not
amount of solute compared to solvent.
numerically
specific
2. Dilute: When a solution has a small amount of
solute compared to solvent.
Which solution is more
concentrated?
3. Saturated: A solution
is saturated if it
contains as much solute
as can possibly be
dissolved under existing
conditions of
temperature and
pressure. (gases only)
4. Unsaturated: Has less
than the maximum
amount that can be
dissolved.
5. Supersaturated: Has more than the
maximum amount that can be dissolved.
Saturated solution of Sodium thiosulfate video clip
The Formation of Solutions:
B. How a Solution forms:
1. Process of dissolving takes place at the surface of
the solute.
Dissolving an Ionic Solute
Ionic solutes break up into
their ions in water
Molecular View of
Solution Formation
Mol M
Solubility Graph for NaNO3
At 20oC, a saturated solution
contains how many grams of
NaNO3 in 100g of water?
What kind of solution is
formed when 90g
NaNO3 is dissolved in
100g water at 30oC?
unsaturated
What kind of solution is
formed when 120g
NaNO3 is dissolved in
100g water at 40oC?
supersaturated
Saturated sol’n
170
160
150
140
Supersaturated
solution
130
120
Solubility ( g/100 g water )
90 g
What is the solubility
at 70oC?
135 g/100 g water
180
110
100
90
80
70
Unsaturated solution
60
50
40
30
20
10
0
0
10
20
30
40
50
60
70
Temperature (deg C)
80
90
100
110
2. The interaction between the solute and solvent to
allow ions to separate is called solvation. This
interaction is called hydration when water is the
solvent.
Water Molecules
Video Clip
3. Energy is absorbed when the bonds between solute and
solvent break.
In the above graph heat is required for the solid to dissolve
so the outside of the test tube would feel cold as it
dissolved. This is an endothermic process.
4. Energy is released when bonds between solute
and solvent form.
In the above graph cold is required for the gas to
dissolve so the outside of the test tube would
feel hot as it dissolved. This is an exothermic
process.
C. Solubility
1. Solubility is the amount of solute that will
dissolve in a given amount of solvent at a certain
temperature (pressure – for gases)
2. Factors that affect solubility:
A. Nature of Solute and Solvent:
General rule:
like dissolves like
polar
in
polar
nonpolar in
nonpolar
Example: iodine in CCl4 (both nonpolar)
salt in water (both polar – ionic)
Solubility of Polar Substances
• Ethanol is soluble in water because of the polar OH bond
• “Like Dissolves Like”
Why is solid sugar soluble in water?
Some substances are Immisible in
Water
• Nonpolar oil does not
interact with polar
water.
• Water-water hydrogen
bonds keep the water
from mixing with the
nonpolar molecules.
B. Temperature:
1. As temperature increases, the solubility of gases
decreases.
Ex) trout need high dissolved oxygen – what type
of climate would be better?
2. For an endothermic solid: If the temperature drops
when the solute and solvent are mixed, raising the
temperature will increase solubility.
3. For an exothermic solid: If the temperature rises
when the solute and solvent are mixed, raising the
temperature will decrease solubility.
Gases are less soluble at high
temperatures than at low temperatures.
C. Pressure:
1. As pressure increases over a gas, solubility
increases.
3. Factors that affect the Rate
of Dissolving:
A. surface area (crushing)
B. stirring
C. temperature
D. All three of these factors
affect the area over which
the solvent can come into
contact with the solute.
In Chemistry concentration is usually measured in
Molarity = moles per liter
Which solution is more
concentrated?
• In chemistry, the units used for concentration are
called molarity.
Which solution has a higher
concentration?
D. Molarity: (M)
molarity =
moles of solute
liters of solution
M =
n
V
units =
mol
L
Ex #1) What is the molarity of a solution formed
by mixing 10.0 g of sulfuric acid with enough
water to make 100.0 mL of solution?
10.0 g H 2SO4
 1 mol H SO
2
4

 98.1 g H 2SO4


 = 0.102 mol H 2SO4


0.102 mol
M =
 1.02 M
0.1000 L H 2 O
Ex #2) How many grams of bromine are needed to
prepare 0.500 L of a 0.0100 M solution of bromine in
water?
n
0.0100 M =
n = 0.00500 mol Br2
0.500 L
 159.8 g Br2 
0.00500 mol Br2 
 = 0.799 g Br2
 1 mol Br 2 
Ex #3) Describe how would you prepare 100.0 mL of
0.7500 M potassium nitrate?
n
0.7500 M KNO3 =
n = 0.07500 mol KNO3
0.1000 L
 101.1 g KNO 
3
0.07500 mol KNO3 
 = 7.583 g KNO3
 1mol KNO3 


Dissolve 7.583 g KNO3 in 100.0 mL of solution.
Ex #4) What volume of 0.600 M sodium hydroxide can
be prepared from 4.8 g of solute?
 1 mol NaOH
4.8 g NaOH 
 40.0 g NaOH


 = 0.12 mol NaOH


0.12 mol NaOH
0.600 M =
V
0.12 mol
V=
= 0.20 L
0.600 mol/L