Chapter 8
Solutions
Solubility
Percent Concentration
Colloids and Suspensions
1
Solute and Solvent
Solutions are homogeneous mixtures of two or
more substances
 Solute
The substance in the lesser amount
 Solvent
The substance in the greater amount
2
Formation of solutions
3
Nature of Solutes in Solutions
 Spread evenly throughout the solution
 Cannot be separated by filtration
 Can be separated by evaporation
 Not visible, solution appears transparent
 May give a color to the solution
4
Types of Solutions
air
O2 gas and N2 gas
gas/gas
soda
CO2 gas in water
gas/liquid
seawater
NaCl in water
solid/liquid
brass
copper and zinc
solid/solid
5
Formation of solutions solvation
H2O
Na+
Hydration
Cl- Na+
Na+
Cl-
H2O
Cl-
Dissolved
solute
solute
6
Formation of solutions creating like-like interactions
Water
Most common solvent
A polar molecule
O a hydrogen bond
H +
H +
7
Formation of solutions creating like-like interactions
8
Formation of solutions creating like-like interactions
When NaCl(s) dissolves in water, the
reaction can be written as
H 2O
NaCl(s)
solid
Na+ (aq) + Cl- (aq)
separation of ions in water
9
Formation of solutions creating like-like interactions
Solid LiCl is added to some water. It dissolves
because
A. The Li+ ions are attracted to the
1) oxygen atom(-) of water
2) hydrogen atom(+) of water
B.
The Cl-- ions are attracted to the
B.
The Cl ions are attracted to the
2) hydrogen atom(+) of water
1) oxygen atom(-) of water
2) hydrogen atom(+) of water
10
Solubility
The maximum amount of solute that can
dissolve in a specific amount of solvent
usually 100 g.
g of solute
100 g water
11
Saturated and Unsaturated
 A saturated solution contains the maximum
amount of solute that can dissolve.
Undissolved solute remains.
 An unsaturated solution does not contain all
the solute that could dissolve
12
Learning Check
At 40C, the solubility of KBr is 80 g/100 g
H2O. Indicate if the following solutions are
(1) saturated or (2) unsaturated
A. ___60 g KBr in 100 g of water at 40C
B. ___200 g KBr in 200 g of water at 40C
C. ___25g KBr in 50 g of water at 40C
13
Solution
At 40C, the solubility of KBr is 80 g/100 g
H2O. Indicate if the following solutions are
(1) saturated or (2) unsaturated
A. 2 Less than 80 g/100 g H2O
B. 1 Same as 100 g KBr in 100 g of water
at 40C, which is greater than its solubility
C. 2 Same as 60 g KBr in 100 g of water,
which is less than its solubility
14
Temperature and Solubility of
Solids
Temperature
0°
20°C
50°C
100°C
Solubility (g/100 g H2O)
KCl(s)
NaNO3(s)
27.6
74
34.0
88
42.6
114
57.6
182
The solubility of most solids (decreases or
increases ) with an increase in the
temperature.
15
Temperature and Solubility of
Solids
Temperature
0°
20°C
50°C
100°C
Solubility (g/100 g H2O)
KCl(s)
NaNO3(s)
27.6
74
34.0
88
42.6
114
57.6
182
The solubility of most solids increases with an
increase in the temperature.
16
Temperature and Solubility of
Gases
Temperature
0°C
20°C
50°C
Solubility
(g/100 g H2O)
CO2(g)
O2(g)
0.34
0.17
0.076
0.0070
0.0043
0.0026
The solubility of gases (decreases or increases)
with an increase in temperature.
17
Temperature and Solubility of
Gases
Temperature
Solubility (g/100 g H2O)
CO2(g)
0°C
20°C
50°C
O2(g)
0.34
0.0070
0.17
0.0043
0.076 0.0026
The solubility of gases decreases with an
increase in temperature.
18
Learning Check
A. Why would a bottle of carbonated drink
possibly burst (explode) when it is left out in
the hot sun ?
B. Why would fish die in water that gets too
warm?
19
Solution
A. Gas in the bottle builds up as the gas becomes
less soluble in water at high temperatures,
which may cause the bottle to explode.
B. Because O2 gas is less soluble in warm water,
the fish may not obtain the needed amount of
O2 for their survival.
20
Soluble and Insoluble Salts
A soluble salt is an ionic compound that
dissolves in water.
An insoluble salt is an ionic compound that
does not dissolve in water
21
Solubility Rules
1. A salt is soluble in water if it contains any
one of the following ions:
NH4+
Li+
Na+
K+ or
NO3-
Examples:
soluble salts
LiCl
Na2SO4
KBr
Ca(NO3)2
22
Cl- Salts
2. Salts with Cl- are soluble, but not if the
positive ion is Ag+, Pb2+, or Hg22+.
Examples:
soluble
not soluble(will not dissolve)
MgCl2
AgCl
PbCl2
23
SO42- Salts
3. Salts with SO42- are soluble, but not if the
positive ion is Ba2+, Pb2+, Hg2+ or Ca2+.
Examples:
soluble
not soluble
MgSO4
BaSO4
PbSO4
24
Other Salts
4. Most salts containing CO32-, PO43-, S2- and
OH- are not soluble.
Examples:
soluble
not soluble
Na2CO3
CaCO3
K2S
CuS
25
Learning Check
Indicate if each salt is (1)soluble or (2)not
soluble:
A. ______ Na2SO4
B. ______ MgCO3
C. ______ PbCl2
D. ______ MgCl2
26
Solution
Indicate if each salt is (1) soluble or (2) not
soluble:
A. _1_ Na2SO4
B. _2_ MgCO3
C. _2_ PbCl2
D. _1_ MgCl2
27
Molarity (M)
A concentration that expresses the
moles of solute in 1 L of solution
Molarity (M) =
moles of solute
1 liter solution
28
Units of Molarity
2.0 M HCl
=
2.0 moles HCl
1 L HCl solution
6.0 M HCl
=
6.0 moles HCl
1 L HCl solution
29
Molarity Calculation
NaOH is used to open stopped sinks, to treat
cellulose in the making of nylon, and to
remove potato peels commercially.
If 4.0 g NaOH are used to make 500. mL of NaOH
solution, what is the molarity (M) of the solution?
30
Calculating Molarity
1) 4.0 g NaOH x 1 mole NaOH = 0.10 mole NaOH
40.0 g NaOH
2) 500. mL x
1L_
= 0.500 L
1000 mL
3. 0.10 mole NaOH
0.500 L
= 0.20 mole NaOH
1L
= 0.20 M NaOH
31
Learning Check
A KOH solution with a volume of 400 mL
contains 2 mole KOH. What is the molarity
of the solution?
1) 8 M
2) 5 M
3) 2 M
32
Solutions
A KOH solution with a volume of 400 mL
contains 2 moles of KOH. What is the
molarity of the solution?
2) 5 M
M = 2 mole KOH = 5 M
0.4 L
33
Learning Check
A glucose solution with a volume of 2.0 L
contains 72 g glucose (C6H12O6). If glucose
has a molar mass of 180. g/mole, what is the
molarity of the glucose solution?
1) 0.20 M
2) 5.0 M
3) 36 M
34
Solution
A glucose solution with a volume of 2.0 L
contains 72 g glucose (C6H12O6). If glucose
has a molar mass of 180. g/mole, what is the
molarity of the glucose solution?
1) 72 g
x
1 mole x
180. g
1
= 0.20 M
2.0 L
35
Molarity Conversion Factors
A solution is a 3.0 M NaOH.. Write the
molarity in the form of conversion factors.
3.0 moles NaOH and
1 L NaOH soln
NaOH
1 L NaOH soln
3.0 moles
36
Learning Check
Stomach acid is a 0.10 M HCl solution. How
many moles of HCl are in 1500 mL of stomach
acid solution?
1) 15 moles HCl
2) 1.5 moles HCl
3) 0.15 moles HCl
37
Solution
3) 1500 mL x
1 L
= 1.5 L
1000 mL
1.5 L x 0.10 mole HCl = 0.15 mole HCl
1L
(Molarity factor)
38
Learning Check
How many grams of KCl are present in 2.5
L of 0.50 M KCl?
1) 1.3 g
2) 5.0 g
3) 93 g
39
Solution M4
3)
2.5 L x 0.50 mole x 74.6 g KCl = 93 g KCl
1L
1 mole KCl
40
Learning Check
How many milliliters of stomach acid, which
is 0.10 M HCl, contain 0.15 mole HCl?
1) 150 mL
2) 1500 mL
3) 5000 mL
41
Solution
2) 0.15 mole HCl x 1 L soln
x 1000 mL
0.10 mole HCl
1L
(Molarity inverted)
= 1500 mL HCl
42
Learning Check
How many grams of NaOH are required to
prepare 400. mL of 3.0 M NaOH solution?
1) 12 g
2) 48 g
3) 300 g
43
Solution
2) 400. mL x 1 L
= 0.400 L
1000 mL
0.400 L x 3.0 mole NaOH x 40.0 g NaOH
1L
1 mole
NaOH
(molar mass)
= 48 g NaOH
44
Learning Check
Amount
12mol
6mol
1.2mol
0.0023mol
1.25mol
0.010mol
Volume
100L
5.0L
300mL
100mL
20L
0.38L
Concentration
0.100molL-1
4.30molL-1
0.632molL-1
8molL-1
Learning Check
Chemical
Molar
mass
Mass
Amount
Volume
NaCl
100g
1.00L
HCl
5.00g
1.33L
Concentration
HNO3
1.20mol
3.00molL-1
NaOH
2.00mol
0.101molL-1
Ca(OH)2
1.32kg
500mL
K2Cr2O7
100mg
20mL
KMnO4
20g
6.00x102mol
1.00molL-1
Na2S2O3
0.38g
1.22x10-4
mol
0.225molL-1