Chapter Eight
Solutions
Solutions
Ocean water is one of
many examples of a
solution in which many
different substances
are dissolved.
Steve Allen/Peter Arnold, Inc.
Chapter 8 | Slide 2 of 55
Solutions
An example not often
considered: Jewelry
often involves solid
solutions in which
one metal has been
dissolved in another
metal.
© Coco McCoy/Rainbow
Chapter 8 | Slide 3 of 55
Solutions cont’d
Fig. 8.1 The making of a solution.
The colored crystals are the solute, and the clear liquid is the
solvent. Stirring produces the solution.
Chapter 8 | Slide 4 of 55
Solutions: Some Basic Terms
• Solution:
– A _______geneous mixture composed of a _________ and a
___________
• Solvent:
– The component of a mixture that is present in the _____________
amount
• Solute:
– The component of a mixture that is present in the _____________
amount
– Remain ____________ distributed and do not _________ out
– Can be _______________ from solvent by _________ means such
as _________________
Chapter 8 | Slide 5 of 55
Solubility
• The ______________ amount of solute that will
dissolve in a ___________ amount of solvent
under a particular set of conditions
Chapter 8 | Slide 6 of 55
Chapter 8 | Slide 7 of 55
Factors Affecting Solubility, I
• Pressure:
– The solubility of gases in liquids ______________ with pressure
– Carbonated beverages are bottled with a partial pressure of CO2 > 1 atm.
– As the bottle is opened, the partial pressure of CO2 decreases and the solubility
of CO2 decreases.
– Therefore, bubbles of CO2 escape from solution.
Chapter 8 | Slide 8 of 55
Solutions
Carbon dioxide
escaping from an
opened bottle of a
carbonated
beverage.
Chapter 8 | Slide 9 of 55
Factors Affecting Solubility, II
• Pressure has ____________ effect on the
solubility of solids or liquids
• Temperature
– The solubility of gases in liquids ________________
with increased temperature
– In general, the solubility of solids in liquids increases
with increased temperature
Chapter 8 | Slide 10 of 55
Chapter 8 | Slide 11 of 55
Amounts of Solute in Solution
• Saturated Solution
– A solution that contains the ________________ amount of solute
that can be dissolved under the conditions at which the solution
exists
– Dissolved solute is in ______________ with undissolved solute
• Supersaturated solution
– An ____________ solution that temporarily contains _________
dissolved solute than that present in a saturated solution
• Unsaturated Solution
– A solution which contains ______ than the maximum amount of
solute that can be dissolved under the conditions at which the
solution exists.
Chapter 8 | Slide 12 of 55
Amounts of Solute in Solution
• Saturated Solution
– A solution that contains the maximum amount of solute that can be
dissolved under the conditions at which the solution exists
– Dissolved solute is in equilibrium with undissolved solute
• Supersaturated solution
– An unstable solution that temporarily contains more dissolved
solute than that present in a saturated solution
http://www.stevespanglerscience.com/content/science-video/supersaturated-solution
• Unsaturated Solution
– A solution which contains less than the maximum amount of solute
that can be dissolved under the conditions at which the solution
exists.
Chapter 8 | Slide 13 of 55
Solutions
← Fig. 8.3
In a saturated solution,
the dissolved solute is
in dynamic equilibrium
with the undissolved
solute.
Chapter 8 | Slide 14 of 55
Solutions
Both solutions contain
the _________ amount
of solute.
A Concentrated
solution (left) contains
a relatively large
amount that could
dissolve in solvent.
A Dilute solution
contains a relatively
small amount of solute
compared with the
amount that could
dissolve in solvent.
Not Strong or Weak
Chapter 8 | Slide 15 of 55
Types of Solutions
• Aqueous Solutions
– ___________ is the solvent
• Nonaqueous Solutions
– The solvent is something other than __________
Chapter 8 | Slide 16 of 55
Solution Formation
To form a solution, solutesolute interactions and
solvent-solvent
interactions must be
broken to form new
solute-solvent
interactions.
Ionic solutes:
Form hydrated ions
Covalent solutes:
Molecules are
hydrated
Chapter 8 | Slide 17 of 55
Rates of Solution Formation
• Solute particles will be more rapidly distributed
throughout a solvent when
– The solute is __________ (has more ___________
______)
– The mixture is ___________
– The _______________ of the solution is ____________
Chapter 8 | Slide 18 of 55
Solubility Rules
• “Like Dissolves Like”
– Nonpolar solutes dissolve in nonpolar solvents
– Polar solutes dissolve in polar solvents
• Rule is not sufficient in the case of ionic solutes dissolved
in water
– Some ionic compounds dissolve in water, but some do not
– We follow a set of experimentally-derived rules to determine which
ionic compounds dissolve in water
Chapter 8 | Slide 19 of 55
Chapter 8 | Slide 20 of 55
Concentration Terms
• Concentration
– Designates the amount of __________ dissolved in a given
___________ of _____________
• There are many ways of designating concentration.
– Percent concentration
• Percent by mass (m/m)
• Percent by volume (v/v)
• Mass-volume percent (m/v)
– Molarity
• Moles / Liter
Chapter 8 | Slide 21 of 55
Percent by Mass
• The mass of solute in a solution divided by the mass of
the solution, multiplied by 100
mass of solute
Percent by mass 
x 100
mass of solution
Solution = solute + solvent
Chapter 8 | Slide 22 of 55
Percent by Volume
• Used when solute and solvent are liquids or gases
• The volume of solute in a solution divided by the volume
of the solution, multiplied by 100
volume of solute
Percent by volume 
x 100
volume of solution
Solution = solute + solvent
Note: With liquids, volumes of solute and solvent are not always additive
Chapter 8 | Slide 23 of 55
Practice: Percentage Concentrations
• Calculate the mass percent of 2.31 g of LiBr dissolved in 35.0 g
of water
• Normal saline solution that is used to dissolve drugs for
intravenous use is 0.92% (m/v) NaCl in water. How many grams
of NaCl are required to prepare 35.0 mL of normal saline
solution?
Chapter 8 | Slide 24 of 55
Solutions
Identical volumetric
flasks are filled to the
50.0-mL mark with
ethanol and with water.
When the two liquids
are poured into a
100mL volumetric flask,
the volume is seen to
be less.
Chapter 8 | Slide 25 of 55
Solutions
Fig. 8.7
When volumes of two different liquids are combined, the
volumes are not additive.
Chapter 8 | Slide 26 of 55
Molarity
• Molarity
– A Conversion Factor between the mass of solute and the
volume of solution!!!
moles of solute
Molarity 
volume of solution in liters
Chapter 8 | Slide 27 of 55
Molarity Problems
Determine the molarity of 3 moles of CuSO4 in enough water to make a 6L
solution.
How many mL of 0.125 M NaCl solution must be used to obtain 0.0250 mol of
NaCl?
Chapter 8 | Slide 28 of 55
Molarity Problems
Determine the molarity of 214 g of MgCl2 (molar mass = 95.2 g/mole) in enough
water to make an 750. mL solution.
Chapter 8 | Slide 29 of 55
Molarity Problems
You are asked to prepare 250. mL of a 3.00 M NaOH by starting with solid NaOH.
How many grams of NaOH would you use? What steps would you follow in
making the solution? (molar mass NaOH = 40.0 g/mole)
Chapter 8 | Slide 30 of 55
Making a Solution
• Steps for making a solution:
1. Weigh out the solute, put it in a volumetric flask.
2. Add some water, mix the solute and the solvent.
3. Add water to the line on the volumetric flask.
Chapter 8 | Slide 31 of 55
Solutions
Chapter 8 | Slide 32 of 55
Dilution Problems
• Dilution:
– Adding solvent to an existing solution to decrease the
solution’s concentration.
• Assume that these beakers contain the same solute.
What is different between the two? What is the same?
BEFORE DILUTION:
AFTER DILUTION:
Chapter 8 | Slide 33 of 55
The Big Idea
When Doing Dilution Problems
•
•
THE NUMBER OF MOLES OF SOLUTE STAYS THE SAME!!!!
Start with 250 mL of a 3.0 M solution of NaOH. Add enough water to have a final
solution volume of 1.0 liter. What is the new concentration of NaOH?
Chapter 8 | Slide 34 of 55
Dilution Problems
Describe how you would prepare 1.0 L of a 0.10 M solution of
sulfuric acid from a 3.0 M solution of sulfuric acid.
Chapter 8 | Slide 35 of 55
Dilution Problems
How many liters of 6.0 M NaOH would be used to prepare 1L of
1.5 M NaOH?
Chapter 8 | Slide 36 of 55
Colloidal Suspension
• Mixtures that contain dispersed particles that are
_______________ in size between those of a true
solution and those of an ordinary heterogeneous
mixture
• Made up of two parts:
– Dispersed phase (similar to the solute)
– Dispersing medium (similar to the solvent)
• Examples:
– Milk
– Blood
Chapter 8 | Slide 37 of 55
Solutions
→ Fig. 8.10
A beam of light travels
through a true solution
without being
scattered. This is not
the case for a colloidal
dispersion.
Chapter 8 | Slide 38 of 55
Colligative Properties
• Some physical properties of solutions depend on the
number of particles dissolved in solution
– Vapor Pressure Lowering
• The more particles dissolved in solution, the lower the vapor
pressure of the solution.
– Boiling Point Elevation
• The more particles dissolved in solution, the higher the boiling
point of the solution.
– Freezing Point Depression
• The more particles dissolved in solution, the lower the freezing
point.
Chapter 8 | Slide 39 of 55
Determining the Number of Particles
in a Solution
• For covalent solutes:
– Number of particles in solution is proportional to the
concentration of the solute in solution (covalent solutes do not
dissociate into ions when they dissolve)
• For ionic solutes:
– Number of particles in solution is proportional to the
concentration of the solute in solution TIMES the number of ions
in the compound (ionic solutes dissociate into ions when they
dissolve; for every NaCl that dissolves in water, you get 2
particles: an Na+ and a Cl-)
Chapter 8 | Slide 40 of 55
How Many Particles Are in These
Solutions?
Solute
M
Moles of Particles in 1 L
Solution
Glucose, C6H12O6 0.60 M
Sucrose,
C12H22O11
0.60 M
FeI3
0.24 M
KF
0.50 M
Chapter 8 | Slide 41 of 55
Which of the Following Solutions Has the
Highest Boiling Point?
• a) 0.100 M CaCl2
• b) 0.200 M Na(OH)
• c) 0.050 M K2(SO4)
• d) 0.050 M Al2(SO4)3
• e) 0.200 M CH3OH
Chapter 8 | Slide 42 of 55
Solutions
Fig. 8.11
Close-ups of the surface of a liquid solvent before and after
solute has been added.
Chapter 8 | Slide 43 of 55
Osmosis and Osmotic Pressure
• Osmosis
– The passage of a solvent through a _______________
membrane separating a dilute solution (or pure solvent)
from a more concentrated solution
• Semipermeable membrane
– A membrane that allows certain types of molecules to
pass through it but prohibits the passage of other types
of molecules (usually based on the size of the particles)
Chapter 8 | Slide 44 of 55
Solutions
Fig. 8.13
(a) Osmosis can be observed with this apparatus. (b) The liquid
level in the tube rises until equilibrium is reached.
Chapter 8 | Slide 45 of 55
Solutions
Fig. 8.14
Enlarged views of a semi-permeable membrane separating (a) pure
water and a salt-water solution, and (b) a dilute salt-water solution.
Chapter 8 | Slide 46 of 55
Osmotic Pressure
• A colligative property
– Increases with the number of particles in solution
• Osmolarity
– The product of a solution’s molarity and the number of
particles produced per formula unit if the solute
dissociates
– Mxi
Chapter 8 | Slide 47 of 55
Solutions
→ Fig. 8.15
Osmotic pressure is the
amount of pressure
needed to prevent the
solution in the tube
from rising as a result
of the process of
osmosis.
Chapter 8 | Slide 48 of 55
Differences in Osmotic Pressure Regulate
Solvent Flow
• Solvent will flow from the solution with ________ osmotic
pressure (concentration of solute) to the solution with
__________ osmotic pressure (concentration of solute)
– Isotonic Solution
• A solution with an osmotic pressure that is equal to that within cells
– Hypertonic Solution
• A solution with a higher osmotic pressure than that within cells
– Hypotonic Solution
• A solution with a lower osmotic pressure than that within cells
Chapter 8 | Slide 49 of 55
Red Blood Cells and Differences in
Solution Concentrations
Red blood cell in a
hypotonic solution:
swelling and
hemolysis occur
Normal red blood
cell in an isotonic
solution
Red blood cell in
a hypertonic
solution:
shrivelling and
crenation occur
Chapter 8 | Slide 50 of 55
Effects of Osmosis
http://arbl.cvmbs.colostate.edu/hbooks/cmb/cells/pmemb/osmosis.html
Chapter 8 | Slide 51 of 55
Solutions
Chapter 8 | Slide 52 of 55
Chapter 8 | Slide 53 of 55
Solutions
Fig. 8.18
In dialysis, there is a net movement of ions from a region of
higher concentration to a region of lower concentration.
Chapter 8 | Slide 54 of 55
Solutions
→ Fig. 8.19
Impurities can be
removed from a
colloidal dispersion by
using a dialysis
procedure.
Chapter 8 | Slide 55 of 55
Chapter 8 | Slide 56 of 55