This document provides an overview of solutions and colloids. It defines key terms like solvent, solute, solubility, saturated and unsaturated solutions. Factors that affect solubility include nature of solute and solvent, temperature, and pressure. Concentrations of solutions can be expressed as molarity, percent composition, or parts per million. Colligative properties depend only on the number of solute particles and include lowering of vapor pressure, freezing point, and boiling point. Osmosis is the movement of solvent through a semipermeable membrane, and osmotic pressure is the pressure needed to prevent osmosis. Dialysis uses semipermeable membranes to remove small solute molecules from the

1. CHAPTER 6
SOLUTIONS AND COLOIDS
CHEM 103
• Solutions
• Solubility
• Factors affecting solubility
• Colligative properties
• Osmosis
• Dialysis
• Review questions

2. A solution is a homogeneous mixture that is uniform throughout at
the molecular level.
Solvent:Solvent: fraction of a solution in which the other components are
dissolved (usually the most abundant component).
Solute:Solute: substance that is dissolved in a solvent
Solutions
NiNO3
Brass = Cu + Zn
Granite= feldspar + mica + quartzBeer=alcohol + malt + gas + water
solution solution solution Not a solution!!!!
(not homogeneous)

3. If carbon dioxide, sodium chloride, ethanol, and glucose are
dissolved in water, what is the specific term that describes
the role of the water?
1. beer
2. solute
3. solution
4. solvent
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80
81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100
101 102 103 104 105 106 107 108 109 110

5. Characteristics of Solutions
• Uniform particle distribution.
• Does not separate on standing.
• Cannot be separated by filtration.
• For many solvent/solute combinations, it is possible to make
solutions of many different compositions.
• Solutions are transparent.
• Solutions can be separated into pure components (the
separation is a physical change, not a chemical change).

6. Which of the following is NOT a characteristic of a
solution?
1. It will separate while standing.
2. It is transparent.
3. It cannot be separated by filtration.
4. It can be separated into pure
components.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80
81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100
101 102 103 104 105 106 107 108 109 110

7. Solubility
Solubility:Solubility: the maximum amount of a solute that dissolves in a given
amount of solvent at a given temperature.
Solubility is a physical constant.
Each solid has a different solubility in every liquid; those with low
solubility are said to be insolubleinsoluble, those with higher solubility are said to
be soluble.soluble.
Still other liquids are completely
soluble in each other:
ethanol and water.
Some liquids are insoluble in
each other: gasoline in water.
Other liquids have limited solubility
in each other:
Ether in water (6 g/100 g H2O).

8. Saturated solution:Saturated solution: contains the maximum
amount of a solute that can be dissolved at
equilibrium at a given temperature. If we add
more it will not go into solution.
Unsaturated solution:Unsaturated solution: contains less than the
maximum amount of a solute that can be
dissolved at a given temperature.
Supersaturated
Sodium acetate
solution
Supersaturated solution:Supersaturated solution: contains more than
the maximum amount of a solute that can be
dissolved at a given temperature; when this
solution is disturbed in any way, the excess
solute separates.

9. Solubility depends on.....
Nature of the solvent and soluteNature of the solvent and solute
“Like dissolves like” = polar compounds dissolve in polar
solvents and nonpolar compounds in non polar solvents
TemperatureTemperature
The solubility of solids in liquids generally increases as
temperature increases.
The solubility of gases in liquids almost always decreases
as temperature increases.

10. How water dissolves molecular compounds
Nonpolar covalent molecules do not dissolve in water.
Polar covalent molecules dissolve by hydrogen bonding but when the
nonpolar part is considerably larger than the polar part, the molecule
no longer dissolves in water.

11. How water disassociates ionic
compounds
Ions dissolved in water are said to be hydrated
(surrounded by water molecules).

12. PressurePressure
Little effect on the solubility of liquids or solids in each other.
The solubility of a gas in a liquid increases as pressure increases.

13. Percent Composition
weight of solute per volume of solution (w/v)weight of solute per volume of solution (w/v)
10 g of table sugar in 100 mL of solvent = 10 % w/v
weight of solute per weight of solution (w/w)weight of solute per weight of solution (w/w)
10 g of table sugar in 200 g of solvent = 5 % w/w
volume of solute per volume of solution (v/v)volume of solute per volume of solution (v/v)
40 mL of ethanol in 100 mL of solvent = 40 % v/v
100x
solutionvolume
soluteweight
ume(w/v)%Weight/vol =
100x
solutionweight
soluteweight
ght(w/w)%Weight/wei =
100x
solutionvolume
solutevolume
ume(v/v)%volume/vol =

14. What is the percent weight per volume for 750.0
mL of solution containing 250.0 g of NaCl?
1. 0.2500%
2. 0.3333%
3. 25.00%
4. 33.33%
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80
81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100
101 102 103 104 105 106 107 108 109 110

15. Molarity
Moles of solute per liter of solution.
Prepare 2.0 L of 0.15 M NaOH
To prepare this solution, dissolve 12.0 g NaOH in 2.0 L of water
Molarity (M ) =
moles of solute (n)
liter of solution (L)
0.30 mol NaO H
40.0 g NaO H
1 mol NaO H
x = 12.0 g NaO H
0.15 mol NaO H
1 L
x 2.0 L = 0.30 mol NaO H

16. The concentration of NaCl in blood serum is approximately
0.14 M. What volume of serum contains 2.0 g of NaCl?
2.0 g NaCl x 1 mole NaCl = 0.034 mol NaCl
58 g NaCl
L = mol = 0.034 = 0.242 L
M 0.140

17. What is the molarity of 750.0 mL of
solution containing 250.0 g of NaCl?
1. 0.250 M
2. 0.333 M
3. 3.00 M
4. 5.75 M
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20
21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40
41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60
61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80
81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100
101 102 103 104 105 106 107 108 109 110

18. Dilutions
If we dilute a solution, the number of moles of solute
remains the same after dilution as before dilution.
M1V1 = M2V2
PPrepare 200 mL of 3.5 M aqueous solution of acetic acid from a stock
solution 6.0 M acetic acid.
To prepare the desired solution, put 120 mL of 6.0 M acetic in a 200
mL volumetric flask and fill to the mark.
V1 =
3.5 mol x 0.200 L
6.0 mol
= 0.12 L

19. 1. 2.
3. 4.
What volume of an 18.0 M H2SO4 solution is
needed to make 50.0 mL of a 1.50 M solution?

20. Parts Per Million (ppm)
When the amount of solute is very small, as with trace
impurities in water, concentration is often expressed in
parts per million (ppm) or parts per billion (ppb).
Drinking water cannot by US law contain more than 1 x
10-8
g of arsenic per gram of water:
ppm As = 1 x 10-8
g x 106
= 0.01
1g sample
ppb As = 1 x 10-8
g x 109
= 10
1g sample
ppm = mg/kg (L)
ppb = µg/kg (L)

21. Electrolytes
Electrolyte:Electrolyte: a substance that conducts electric
current when dissolved in water; a substance that
does not conduct electricity is called a
nonelectrolyte.nonelectrolyte.
Strong electrolyte:Strong electrolyte: a compound that dissociates
completely to ions in an aqueous solution.
Weak electrolyte:Weak electrolyte: a compound that only partially
dissociates to ions in an aqueous solution.

22. Cations migrate to
the cathodeAnions migrate to anode
The movement of ions creates
an electric current.

23. Colloids
Colloid particles have very large surface areas and scatter light
appearing turbid, cloudy, or milky.

25. Tyndall effect:Tyndall effect: a characteristic of colloids in which light
passing through the colloid scatters
Examples
The beam of a searchlight scattered by the suspended water
droplets in the night air.
Sun beams as the sun light is scattered off the dust particles in
the room air.

26. Why do colloidal particles remain in solution?
Most colloidal particles carry a large solvation layer; if the solvent is
water, as in the case of protein molecules in the blood, the large
number of surrounding water molecules prevents colloidal molecules
from touching and sticking together.
Because of their large surface area, colloidal particles acquire
charges from solution; for example, they all may become negatively
charged. When a charged colloidal particle encounters another
particle of the same charge, they repel each other.

27. Which of the following does not experience the
Tyndall effect?
1. fog
2. clouds
3. smoke
4. water

28. Colligative Properties
Properties that depend on the number of solute
particles, and not on the nature of the particles
are called colligative properties.
Vapor pressure
(lowering)
Freezing point
(depression)
Boiling point
(elevation)
Osmotic pressure

29. Freezing-Point Depression
One mole of any particle dissolved in 1000 grams of
water lowers the freezing point of water by 1.86°C (the
nature of the particles does not matter, only the number of particles).
Applications:
We use NaCl and CaCl2 to melt snow and ice.
We use ethylene glycol as antifreeze in automobile radiators.
∆T =
mol
x mol of particles1.86°C

30. if we add 275 g of ethylene glycol, C2H6O2, per 1000 g of
water in a car radiator, what will be the freezing point of
the solution?
Ethylene glycol is a molecular compound; it dissolves in water without
dissociation.
Freezing point will be lowered from 0 to - 8.26 °C (17.2°F).
275 g ethylene glycol x
1 mol ethylene glycol
62.0 g ethylene glycol
= 4.44 mol ethylene glycol
1 mol ethylene glycol
4.44 mol ethylene glycol x 1.86 °C
= 8.26°C

31. What will be the freezing point of a solution prepared
by dissolving 1.00 mole of K2SO4 in 1000 grams of
water?
K2SO4 is an ionic solid and dissociates to ions when dissolved in water.
One mole of K2SO4 gives three moles of ions.
The freezing point is lowered by 3 x 1.86°C or 5.58°C.
The solution will freeze at -5.58°C.
∆T =
mol
x mol of particles1.86°C

32. Which of the following will have the lowest freezing
point?
1. 2.
3. 4.

33. Osmosis
Movement of solvent particles through a semipermeable membrane from a region of
lower solute concentration to a region of higher solute concentration.
Osmotic pressure:
pressure necessary
to prevent osmosis
Semipermeable membrane: membrane with pores that are big enough to allow solvent molecules to
pass through them, but not big enough to allow the passage of larger solute molecules.

34. Osmolarity (osmol):Osmolarity (osmol): the molarity (M) multiplied by the
number of particles (i) produced by each formula unit of
solute.
Osmolarity = M x i
Hemolysis:Hemolysis: the swelling and bursting of red blood cells because they cannot
resist the increase in osmotic pressure when put into a hypotonic solution.
Isotonic solutionsIsotonic solutions::
solutions with the same
osmolarity
Hypotonic solutionHypotonic solution:: a solution
with lower osmolarity with
respect to another solution.
Hypertonic solutionHypertonic solution:: a solution
with higher osmolarity than red
blood cells.

35. A solution containing 8.9 g of NaCl in 1 L is
referred to as physiological saline solution.
What is the osmolarity (osmol) of this solution?
8.9 g in 1.00 L of solution
each mole of NaCl dissociates into two ions
Then the osmolarity of the solution is 0.15 x 2 = 0.30 osmol
8.9 g NaCl
1 L
x
1 .00 mol NaCl
58.5 g NaCl
= 0.15 mol NaCl
1.00 L
= 0.15 M NaCl

36. Dialysis
An osmotic semipermeable membrane allows only solvent to pass. If the
membrane pores are made somewhat larger then small solute molecules
but not large ones can also get through. This is called dyalisis.
The isotonic solution (dialysate) used in
hemodialysis is isotonic with blood for
NaCl, glucose, K, and bicarbonate ions.
The membrane pores are small and let
urea (body waste) pass through but not
large protein molecules present in
blood.