Slide 1 ___________________________________
___________________________________ ___________________________________ ___________________________________ ___________________________________ Physical Properties of Solutions
___________________________________ Chapter 13
___________________________________ 1
Copyright © The McGraw-Hill Companies, Inc. Permission required for reproduction or display.
___________________________________
Slide 2 A solution is a homogenous mixture of 2 or
more substances
___________________________________ The solute is(are) the substance(s) present in the
smaller amount(s)
___________________________________ ___________________________________ The solvent is the substance present in the larger
amount
___________________________________ ___________________________________ ___________________________________ 2
Slide 3 ___________________________________
A saturated solution contains the maximum amount of a
solute that will dissolve in a given solvent at a specific
temperature.
___________________________________ An unsaturated solution contains less solute than the
solvent has the capacity to dissolve at a specific
temperature.
___________________________________ ___________________________________ A supersaturated solution contains more solute than is
present in a saturated solution at a specific temperature.
___________________________________ Sodium acetate crystals rapidly form when a seed crystal is
added to a supersaturated solution of sodium acetate.
___________________________________ ___________________________________ 3
Slide 4 ___________________________________
Three types of interactions in the solution process:
• solvent-solvent interaction
• solute-solute interaction
• solvent-solute interaction
___________________________________ Molecular view of the formation of solution
___________________________________ ___________________________________ ___________________________________ ___________________________________ ∆Hsoln = ∆H1 + ∆H2 + ∆H3
___________________________________ 4
___________________________________
Slide “like dissolves like”
5 ___________________________________ Two substances with similar intermolecular forces are likely
to be soluble in each other.
___________________________________ •
___________________________________ non-polar molecules are soluble in non-polar solvents
CCl4 in C6H6
•
___________________________________ polar molecules are soluble in polar solvents
C2H5OH in H2O
•
___________________________________ ionic compounds are more soluble in polar solvents
___________________________________ NaCl in H2O or NH3 (l)
5
Slide ___________________________________
Concentration Units
6 ___________________________________ The concentration of a solution is the amount of solute
present in a given quantity of solvent or solution.
___________________________________ Percent by Mass
% by mass =
=
___________________________________ mass of solute
x 100%
mass of solute + mass of solvent
___________________________________ mass of solute x 100%
mass of solution
___________________________________ Mole Fraction (X)
moles of A
XA =
sum of moles of all components
___________________________________ 6
___________________________________
Slide Concentration Units Continued
7 ___________________________________ Molarity (M)
M =
___________________________________ moles of solute
liters of solution
___________________________________ ___________________________________ Molality (m)
m =
___________________________________ moles of solute
mass of solvent (kg)
___________________________________ 7
___________________________________
Slide 8 What is the molality of a 5.86 M ethanol (C2H5OH) solution
whose density is 0.927 g/mL?
___________________________________ moles of solute
moles of solute
m =
M =
___________________________________ liters of solution
mass of solvent (kg)
Assume 1 L of solution:
5.86 moles ethanol = 270 g ethanol
927 g of solution (1000 mL x 0.927 g/mL)
___________________________________ ___________________________________ mass of solvent = mass of solution – mass of solute
= 927 g – 270 g = 657 g = 0.657 kg
moles of solute
=
m =
5.86 moles C2H5OH
___________________________________ = 8.92 m
___________________________________ 0.657 kg solvent
mass of solvent (kg)
8
___________________________________
Slide 9 Solution Stoichiometry
___________________________________ The concentration of a solution is the amount of solute
present in a given quantity of solvent or solution.
M = molarity =
___________________________________ moles of solute
___________________________________ liters of solution
___________________________________ What mass of KI is required to make 500. mL of a
2.80 M KI solution?
M KI
volume of KI solution
moles KI
M KI
___________________________________ grams KI
___________________________________ 500. mL x
1L
1000 mL
x
2.80 mol KI
1 L soln
x
166 g KI
1 mol KI
= 232 g KI
9
___________________________________
Slide Preparing a Solution of Known Concentration
10 ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ 10
___________________________________
Slide 11 Dilution is the procedure for preparing a less concentrated
solution from a more concentrated solution.
___________________________________ ___________________________________ ___________________________________ Dilution
___________________________________ Add Solvent
___________________________________ Moles of solute
before dilution (i)
=
Moles of solute
after dilution (f)
MiVi
=
MfVf
___________________________________ 11
___________________________________
Slide 12 How would you prepare 60.0 mL of 0.200 M HNO3
from a stock solution of 4.00 M HNO3?
___________________________________ ___________________________________ MiVi = MfVf
Mi = 4.00 M Mf = 0.200 M Vf = 0.0600 L
Vi =
MfVf
Mi
___________________________________ Vi = ? L
___________________________________ = 0.200 M x 0.0600 L = 0.00300 L = 3.00 mL
4.00 M
___________________________________ ___________________________________ Dilute 3.00 mL of acid with water to a total volume
of 60.0 mL.
12
Slide 13 ___________________________________
Titrations
In a titration a solution of accurately known concentration is
added gradually added to another solution of unknown
concentration until the chemical reaction between the two
solutions is complete.
___________________________________ Equivalence point – the point at which the reaction is complete
___________________________________ Indicator – substance that changes color at (or near) the
equivalence point
___________________________________ ___________________________________ Slowly add base
to unknown acid
UNTIL
___________________________________ ___________________________________ the indicator
changes color
13
Slide ___________________________________
Titrations can be used in the analysis of
14 ___________________________________ Acid-base reactions
___________________________________ H2SO4 + 2NaOH
2H2O + Na2SO4
___________________________________ ___________________________________ Redox reactions
___________________________________ ___________________________________ 5Fe2+
-
+ MnO4 +
8H+
Mn2+
+
5Fe3+
+ 4H2O
14
___________________________________
Slide 15 What volume of a 1.420 M NaOH solution is required
to titrate 25.00 mL of a 4.50 M H2SO4 solution?
___________________________________ ___________________________________ WRITE THE CHEMICAL EQUATION!
H2SO4 + 2NaOH
___________________________________ 2H2O + Na2SO4
___________________________________ M
volume acid
25.00 mL x
acid
rxn
moles red
4.50 mol H2SO4
1000 mL soln
x
coef.
M
moles base
2 mol NaOH
1 mol H2SO4
x
base
volume base
1000 ml soln
1.420 mol NaOH
___________________________________ ___________________________________ = 158 mL
15
Slide 16 ___________________________________
16.42 mL of 0.1327 M KMnO4 solution is needed to
oxidize 25.00 mL of an acidic FeSO4 solution. What is
the molarity of the iron solution?
___________________________________ WRITE THE CHEMICAL EQUATION!
5Fe2+ + MnO4- + 8H+
Mn2+ + 5Fe3+ + 4H2O
___________________________________ ___________________________________ M
volume red
red
rxn
moles red
coef.
V
moles oxid
oxid
___________________________________ M oxid
___________________________________ 16.42 mL = 0.01642 L
0.01642 L x
0.1327 mol KMnO4
1L
25.00 mL = 0.02500 L
x
5 mol Fe2+
1 mol KMnO4
x
1
0.02500 L Fe2+
___________________________________ = 0.4358 M
16
Slide ___________________________________
Temperature and Solubility
17 ___________________________________ Solid solubility and temperature
___________________________________ ___________________________________ solubility increases with
increasing temperature
___________________________________ solubility decreases with
increasing temperature
___________________________________ ___________________________________ 17
Slide ___________________________________
Temperature and Solubility
18 ___________________________________ O2 gas solubility and temperature
___________________________________ ___________________________________ solubility usually
decreases with
increasing temperature
___________________________________ ___________________________________ ___________________________________ 18
Slide ___________________________________
Pressure and Solubility of Gases
19 ___________________________________ The solubility of a gas in a liquid is proportional to the
pressure of the gas over the solution (Henry’s law).
___________________________________ c is the concentration (M) of the dissolved gas
c = kP
P is the pressure of the gas over the solution
___________________________________ k is a constant for each gas (mol/L•atm) that
depends only on temperature
___________________________________ ___________________________________ low P
high P
low c
high c
___________________________________ 19
Slide ___________________________________
Colligative Properties
20 ___________________________________ Colligative properties are properties that depend only on the
number of solute particles in solution and not on the nature
of the solute particles.
___________________________________ Vapor-Pressure Lowering
P1 = X1 P 10
___________________________________ P 10 = vapor pressure of pure solvent
Raoult’s law
___________________________________ X1 = mole fraction of the solvent
___________________________________ If the solution contains only one solute:
___________________________________ X1 = 1 – X2
P 10 - P1 = ∆P = X2 P 10
X2 = mole fraction of the solute
20
___________________________________
Slide 21 ___________________________________ Ideal Solution
PA = XA P A0
___________________________________ PB = XB P 0B
PT = PA + PB
___________________________________ PT = XA P A0 + XB P 0B
___________________________________ ___________________________________ ___________________________________ 21
___________________________________
Slide 22 Boiling-Point Elevation
___________________________________ ∆Tb = Tb – T b0
T b0 is the boiling point of
the pure solvent
T b is the boiling point of
the solution
Tb > T b0
___________________________________ ___________________________________ ∆Tb > 0
___________________________________ ∆Tb = Kb m
___________________________________ m is the molality of the solution
___________________________________ Kb is the molal boiling-point
elevation constant (0C/m)
for a given solvent 22
___________________________________
Slide 23 Freezing-Point Depression
___________________________________ ∆Tf = T 0f – Tf
T
0
Tf
f
is the freezing point of
the pure solvent
is the freezing point of
the solution
T 0f > Tf
___________________________________ ___________________________________ ∆Tf > 0
___________________________________ ∆Tf = Kf m
___________________________________ m is the molality of the solution
___________________________________ Kf is the molal freezing-point
depression constant (0C/m)
for a given solvent 23
___________________________________
Slide 24 ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ 24
___________________________________
Slide 25 What is the freezing point of a solution containing 478 g of
ethylene glycol (antifreeze) in 3202 g of water? The molar mass
of ethylene glycol is 62.01 g.
∆Tf = Kf m
___________________________________ ___________________________________ Kf water = 1.86 oC/m
478 g x
moles of solute
1 mol
62.01 g
___________________________________ =
m =
= 2.41 m
3.202 kg solvent
mass of solvent (kg)
___________________________________ ∆Tf = Kf m = 1.86 oC/m x 2.41 m = 4.48 oC
___________________________________ ∆Tf = T 0f – Tf
Tf = T f – ∆Tf = 0.00
0
___________________________________ oC
– 4.48
oC
= -4.48
oC
25
Slide 26 Osmotic Pressure (π)
___________________________________
Osmosis is the selective passage of solvent molecules through a porous
membrane from a dilute solution to a more concentrated one.
___________________________________ A semipermeable membrane allows the passage of solvent molecules but
blocks the passage of solute molecules.
___________________________________ Osmotic pressure (π) is the pressure required to stop osmosis.
___________________________________ ___________________________________ ___________________________________ more
concentrated
dilute
___________________________________ 26
Slide ___________________________________
Osmotic Pressure (π)
27 ___________________________________ ___________________________________ time
solvent
High
P
solution
___________________________________ ___________________________________ Low
P
___________________________________ π = MRT
___________________________________ M is the molarity of the solution
R is the gas constant
T is the temperature (in K)
27
Slide ___________________________________
A cell in an:
28 ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ ___________________________________ isotonic
solution
hypotonic
solution
hypertonic
solution 28
Slide ___________________________________
Colligative Properties
29 ___________________________________ Colligative properties are properties that depend only on the
number of solute particles in solution and not on the nature of
the solute particles.
___________________________________ Vapor-Pressure Lowering
P1 = X1 P 10
___________________________________ Boiling-Point Elevation
∆Tb = Kb m
___________________________________ Freezing-Point Depression
∆Tf = Kf m
___________________________________ π = MRT
Osmotic Pressure (π)
___________________________________ 29
Slide ___________________________________
Colligative Properties of Electrolyte Solutions
30 ___________________________________ 0.1 m Na+ ions & 0.1 m Cl- ions
0.1 m NaCl solution
Colligative properties are properties that depend only on the
number of solute particles in solution and not on the nature of
the solute particles.
___________________________________ ___________________________________ 0.2 m ions in solution
0.1 m NaCl solution
van’t Hoff factor (i) =
___________________________________ actual number of particles in soln after dissociation
number of formula units initially dissolved in soln
___________________________________ i should be
nonelectrolytes
NaCl
CaCl2
___________________________________ 1
2
3
30
Slide ___________________________________
Colligative Properties of Electrolyte Solutions
31 Boiling-Point Elevation
∆Tb = i Kb m
___________________________________ Freezing-Point Depression
∆Tf = i Kf m
___________________________________ π = iMRT
___________________________________ Osmotic Pressure (π)
___________________________________ ___________________________________ ___________________________________ 31
___________________________________
Slide 32 CH-13 HW
___________________________________ ___________________________________ Questions and Problems
Pages 131 - 132
___________________________________ 4.54, 4.56, 4.58, 4.60, 4.64, 4.66,
4.68, 4.78, 4.80.
___________________________________ Pages 459 - 460
___________________________________ 13.8, 13.10, 13.14, 13.16, 13.18,
13.20 (molarity only), 13.22, 13.26.
___________________________________ 32