1. Topic 7
Solutions

2. Topic 7-Solutions
Solutions
a. Types of solutions
b. Properties
c. Solute
d. Solvent
Factors that affect solubility
a. Nature of solute and solvent
b. Temperature
c. Pressure
Factors affecting rate of solubility
a. Concentration of solute
d. Stirring
e. Surface area
4. a. Unsaturated/Saturated/Supersaturated
b. Dilute vs. Concentrated
5. Concentration of solutions
a. Molarity-Table T
b. Percent by mass-Table T
c. Percent by volume
d. Parts per million-Table T
Preparation of a Solution of
Known Concentration
Colligative Properties
ionic vs. molecular substances
a. Freezing point depression
b. Boiling point elevation
c. Vapor pressure depression

3. Solid-brass (Cu & Zn) & bronze (Cu & Sn)
Types of Solutions
Solid-brass (Cu & Zn) & bronze (Cu & Sn)
Alloy-a mixture composed of two or more elements,
at least one of which is a metal
Liquid-soda (Water, CO2 (g) & flavoring)
Gas-air

4. Properties of Solutions
Homogeneous mixture-each part of the solution retains its
original properties-only physically combined
2. Clear/doesn’t disperse light-but can have color
3. Particles do not settle upon standing
4. Pass through a filter-cannot be separated by filtering

5. Parts of a Solution
1. Solute-
Dissolved particles in a solution
2. Solvent-
The dissolving medium in a solution
We indicate a solution by using the notation (aq)
It indicates that the substance is mixed (dissolved in water)
Ex.: NaCl (s)-solid
NaCl (l) –liquid (melted)
NaCl (g)-gas
NaCl (aq)-mixed with water
If the solvent is alcohol, the solution is called a tincture
Tincture of iodine is iodine dissolved in alcohol

6. Polar substances dissolve other polar substances
Factors that affect Solubility
Why do some things dissolve and other don’t?
1. Nature of the solvent and solute-like dissolves like
Polar substances dissolve other polar substances
and ionic substances
Nonpolar substances dissolve other nonpolar substances
*remember: water is polar so if it dissolves in water, it is polar or ionic…if it doesn’t dissolve in water it is nonpolar
polar
So…sugar dissolved in water so sugar must be?
nonpolar
Grease doesn’t dissolve in water so grease must be?

7. This is why we refrigerate opened cans/bottles of soda so that
2. Temperature
For most substances:
As temperature increases, solubility increases
As temperature decreases, solubility decreases
What type of solution does not follow this trend?
Solutions with gases (think soda!)
As temperature increases, solubility decreases
As temperature decreases, solubility increases
This is why we refrigerate opened cans/bottles of soda so that
they don’t go flat

9. three substances on Table G must be gases dissolved in water?
Now look at Table G
Knowing what we know about temperature and solubility, which
three substances on Table G must be gases dissolved in water?
NH3, SO2 and HCl

10. Pressure has very little effect on solutions containing solids
and liquids but does have a great affect on solutions containing
gases
Increase pressure = increase in solubility of gases
Decrease pressure = decrease in solubility of gases
This is why soda is manufactured and stored under high pressure!

11. As pressure increases, the rate of dissolving of a gas increases
Factors affecting rate of solubility or how fast something dissolves
1. Concentration of Solute already dissolved-
As the amt. of solute dissolved increases, the rate of dissolving will decrease since there is less room for the solute to dissolve
Temperature-
As temp increases, rate of dissolving increases
Except gases: Increase temp = dissolve less
3. Pressure-
As pressure increases, the rate of dissolving of a gas increases
4. Stirring-
will increase the rate of dissolving
5. Surface Area-
Greater surface area = greater rate of dissolving
Smaller size particles dissolve faster than one large particle
Think of granular sugar vs. a cube of sugar
The granular sugar dissolves faster because of more surface area

12. Terms used to describe solutions
Dilute-
A solution that contains a small amount of solute
Concentrated-
A solution containing a large amount of solute
What is wrong with the terms dilute and concentrated?
They are very subjective.
What is a small amount to one person may not be small to another
individual. What is a large amount to one person may not be a
large amount to another person
Therefore, we need terms that take the subjectivity out
of the concentration and give us some “concrete” information

13. Terms used to describe the amount of solute in a solution
Unsaturated solution-
A solution that contains less solute than a saturated solution at
a given temperature and pressure. If additional solute is added,
it will dissolve until the solution is saturated.
Saturated solution-
A solution that contains the maximum amount of solute for a
given quantity of solvent at a given temperature and pressure.
If additional solute is added, it will simply sink to the bottom
of the flask. It is said to be at EQUILIBRIUM
Supersaturated solution-
A solution that contains more solute than it can theoretically
hold at a given temperature. If additional solute is added,
all the excess solute will precipitate out and the solution will
now be saturated

14. Using Reference Table G
You must know what temperature your solution is at and what
your solute is. Then you must determine if you are above, below
or on the line of the solute.
If you are above the solute’s line, the solution is
SUPERSATURATED
If you are on the solute’s line, the solution is
SATURATED
If you are below the solute’s line, the solution is
UNSATURATED

16. Lets pick a temperature, a solute and how much water the solute
Now lets look at Table G
Lets pick a temperature, a solute and how much water the solute
is dissolved in
At 50 C, in 100 g of water, 70 g of KNO3 is dissolved. What type
of solution is this?
Below the KNO3 line-
UNSATURATED
At 50 C, in 100 g of water, 83 g of KNO3 is dissolved. What type
of solution is this?
On the KNO3 line-
SATURATED
At 50 C, in 100 g of water, 100 g of KNO3 is dissolved. What type
of solution is this?
Above the KNO3line-
SUPERSATURATED

17. What if the solute is not dissolved in 100 g of water as the “Y” axis
on Table G is labeled?
We must set up a proportion
Ex.: How much KI is needed to make a saturated solution in
300 g of water at 10 C?
We set up a proportion: 136 g KI = x g KI
100g H2O g H2O
x = 408 g KI
What is the minimum amount of water needed to dissolve 50 g
of NH4Cl to make a saturated solution at 60 C?
58 g of NH4Cl = 50 g NH4Cl
100 g H2O x g H2O
Set up a proportion:
X = g
H2O

18. How do we express the concentration of a solution?
Moles (mol)
Liters
1. Molarity =
(Table T)
2. Percent by mass =
Mass of solute x 100 =
Mass of solution
(Table T)
3. Percent by volume =
Volume of solute x 100 =
Volume of solution
4. Parts per million (ppm) =
Mass of solute x =
Mass of solution
(Table T)

19. Ex. A solution has a volume of 2.0 L and contains 36 g of
Molarity
Ex. A solution has a volume of 2.0 L and contains 36 g of
glucose (C6H12O6). If the molar mass of glucose is 180 g/mol,
what is the molarity of the solution?
1. First convert the # grams into moles if not given in moles .
Mol = grams/molar mass
Mol = = .2 mol
180
2. Now, use the formula for molarity
Molarity = moles L
M = .2 = . 1 M 2

20. What is the percent by mass of a solution that contains
Mass of solute x 100 =
Mass of soln
What is the percent by mass of a solution that contains
100 g of solute in 250 g of solution?
100 g x 100 =
250 g
40 %
*The only “curveball” may be that instead of giving the total
mass of the solution, you will be given the mass of the
solute and the mass of the solvent. Simply add them together
to get the mass of the solution

21. Ex.: If 10 mL of propanone (acetone C3H6O) is diluted with water
Percent by Volume
Volume of solute x 100 =
Volume of soln
Ex.: If 10 mL of propanone (acetone C3H6O) is diluted with water
to a total solution volume of 200 mL, what is the percent by
volume of propanone in this solution?
10 mL x 100 =
200 mL
5 %
*The only “curveball” they may throw is that instead of
giving the total volume of the solution, they will give
the volume of the solute and the volume of the solvent. All you
will have to do is add them to get the volume of the
solution

22. Parts per million (ppm)
Mass of solute x =
Mass of soln
What is the concentration in ppm of a solution that contains .06 g
of solute dissolved in 500 g of water?
.06 g x = g
ppm
*Notice…instead of giving the total volume of the solution in the
question, you were given the volume of the solute and the solvent.
To get the total volume of the solution, add the two together.
*Remember…volume of a solution = vol. of solute + vol. of solvent

23. At times, it becomes necessary to dilute a concentration to a new
Dilution of a Solution
At times, it becomes necessary to dilute a concentration to a new
concentration.
I purchase HCl with a concentration of 18 M and will add
water in order to make solutions of varying concentrations
For a lab, I need 100 mL of 6 M HCl. What volume of 18 M HCl
do I need to use?
M1V1 = M2V2
(6)(100) = (18)(x)
600 = 18x
x = mL of HCl
So I had mL of HCl to a graduate and add water to the 100
mL mark

24. Colligative Properties of Solutions
A property that depends only upon the number of solute particles,
and not upon their identity
There are three (3) colligative properties:
1. Boiling point elevation
2. Freezing point depression
3. Vapor pressure depression
Whenever anything dissolves in water, the solution will have a
higher boiling point, lower freezing point and lower vapor pressure
than pure water

25. lower the fp and the higher the bp
Ionic (M-NM) vs. Molecular (NM-NM) Substances
With all things equal, ionic substances will lower the fp and raise the bp of a solution more than a molecular substance
With all things equal, with ionic substances, the more ions, the
lower the fp and the higher the bp
Which of the following substances will lower the fp and raise the bp of a water solution the greatest?
C6H12O CO2
CaCl NaCl

26. We can immediately eliminate the C6H12O6 and CO2 because they
are molecular (NM-NM)
So between CaCl2 and NaCl, which has the greater effect?
We must dissociate (break up into ions) each of the ionic substances
CaCl2  Ca Cl-
(3 moles of ions)
NaCl  Na+ + Cl-
(2 moles of ions)
Therefore, CaCl2 will have the greater effect (lower fp & higher bp)

27. because it is the most concentrated
Therefore…ionic substances always have a greater effect…lower
the fp and raise the bp of solutions more than molecular substances
The more concentrated a solution is, the greater the effect
Which solution will have the lowest freezing point?
a mole in 1000 ml of water
b moles in 2000 ml of water
c moles in 1000 ml of water
d moles in 2000 ml of water
Find the molarity of each solution
a. 1 M
b. 1 M
c. 3 M
d. 2 M
Therefore…solution c will have the lowest fp and highest bp
because it is the most concentrated

28. Describes liquids that dissolve in one another in all
Just a few terms:
Miscible-
Describes liquids that dissolve in one another in all
proportions
(dissolve without limit-alcohol and water)
Immiscible-
Describes liquids that are insoluble in one another
(oil and water are immiscible)

29. Electrolyte-
A compound that conducts an electric current
when it is in an aqueous solution or in the molten
state; all ionic compounds are electrolytes, but
most covalent compounds are not
Ex.: acids (covalent), bases (covalent) and salts (ionic)
Nonelectrolyte-
A compound that does not conduct an electric
current in aqueous solution or in the molten
state

30. A process that releases heat to its surrounding
Exothermic-
A process that releases heat to its surrounding
Gas  liquid  solid
Endothermic-
A process that absorbs heat from the surrounding
Solid  liquid  gas
BE CAREFUL IF IT IS A SOLUTION
If the temperature of the water goes up, dissolving is exothermic
If the temperature of the water goes down, dissolving is
endothermic
We can’t measure the solute’s temperature directly so we measure
what effect the solute has on the temperature of the water

31. Why do some substances conduct heat or electricity
while others do not?
Why do some compounds only conduct
in one phase and not other phases?
The answer:
Why do some substances conduct?
Free moving charged particles
Why do some substances not conduct?
No free moving charged particles

32. I do not care what type of substance it is:
Ionic, Covalent or Metallic
If it conducts, it is because of free moving charged particles
I do not care what phase of matter it is
If it conducts, it is because of free moving charged particles

33. Why are some substances solid, liquid or gas
at room temperature?
Solid-strong attractive forces (IMFs) between particles
Gas-weak attractive forces (IMFs) between particles
Liquid-average attractive forces (IMFs) between particles

34. Why are some solids hard while others are soft?
Hard-strong attractive forces between particles
Soft-weak attractive forces between particles