The document discusses various properties of solutions including the different states that solutions can exist in, components and relationships in solutions, energy changes during the formation of solutions, factors that affect solubility such as polarity, pressure, and temperature, and colligative properties which are properties that depend only on the number of solute particles and not their type. It also covers topics such as vapor pressure lowering, boiling point elevation, freezing point depression, and osmotic pressure.

1. Properties of Solutions
Chapter 11

2. Solutions
State of State of State of
Example Solution Solute Solvent
Air, natural gas Gas Gas Gas
Rubbing alcohol, antifreeze Liquid Liquid Liquid
Brass Solid Solid Solid
Carbonated water (soda) Liquid Gas Liquid
Seawater, sugar solution Liquid Solid Liquid
Hydrogen in platinum Solid Gas Solid

3. Components of Solution
Relationships Between Amounts of Solute, Solvent and Solution
Molar Mass
Density

4. nsolute msolute Vsolute
Molar Mass
Density
nsolvent msolvent Vsolvent
nsoln msoln Vsoln
molessolute
Molarity (M )
volum esolutionin L

5. nsolute msolute Vsolute
Molar Mass
Density
nsolvent msolvent Vsolvent
nsoln msoln Vsoln
m oles solute
Molality (m)
m ass solvent(kg)

6. nsolute msolute Vsolute
Molar Mass
Density
nsolvent msolvent Vsolvent
nsoln msoln Vsoln
m ass A m ass A
m ass % A 100 100
m ass A m ass B m ass C total m ass solution

7. nsolute msolute Vsolute
Molar Mass
Density
nsolvent msolvent Vsolvent
nsoln msoln Vsoln
m oles A m oles A
Mole fraction A
m oles solution m oles A m oles B m olesC

8. 1. Separating the solute into its individual components
(expanding the solute).
2. Overcoming intermolecular forces in the solvent to
make room for the solute (expanding the solvent).
3. Allowing the solute and solvent to interact to form the
solution.

9. Steps 1 and 2 require energy, since forces must be
overcome to expand the solute and solvent.
Step 3 usually releases energy.
Steps 1 and 2 are endothermic, and step 3 is often
exothermic.

10. Explain why water and oil (a long chain hydrocarbon) do not
mix. In your explanation, be sure to address how ΔH plays a
role.

11. Energy Terms of Various Types
of Solutes and Solvent
H1 H2 H3 Hsoln Outcome
Polar solute, polar Large Large Large, Small Solution
solvent negative forms
Nonpolar solute, polar Small Large Small Large, No solution
solvent positive forms
Nonpolar solute, Small Small Small Small Solution
nonpolar solvent forms
Polar solute, nonpolar Large Small Small Large, No solution
solvent positive forms

12. In General
One factor that favors a process is an
increase in probability of the state
when the solute and solvent are mixed.
Processes that require large amounts of
energy tend not to occur.
Overall, remember that “like dissolves
like”.

13. Factors Affecting Solubility
Structural Effects:
 Polarity
Pressure Effects:
 Henry’s law
Temperature Effects:
 Affecting aqueous solutions

14. Polarity Effects
Ascorbic acid
Detergent

15. Henry’s law: C = kP
C = concentration of dissolved
gas
k = constant
P = partial pressure of gas solute
above the solution
Amount of gas dissolved in a solution is directly
proportional to the pressure of the gas above the
solution.

16. Temperature Effects (for
Aqueous Solutions)
• Although the solubility of most solids in water
increases with temperature, the solubilities of
some substances decrease with increasing
temperature.
• Predicting temperature dependence of
solubility is very difficult
• Solubility of a gas in solvent typically
decreases with increasing temperature.

17. Temperature Dependence of
Solubility of Solids in Aqueous
Solutions

18. Temperature Dependence of
Solubility of Gases in Aqueous
Solutions

19. Temperature Dependence of
Solubility in Aqueous Solutions
 Although the solubility of most solids in water increases
with temperature, the solubilities of some substances
decrease with increasing temperature.
 Predicting temperature dependence of solubility is very
difficult.
 Solubility of a gas in solvent typically decreases with
increasing temperature.

20. Colligative Properties
Properties that depend ONLY on the
number and NOT in the nature of solute
particles.
 Vapor Pressure Lowering
 Boiling Point Elevation
 Freezing Point Elevation
 Osmotic Pressure

21. Equilibrium Vapor Pressure
• The pressure of the vapor due to the evaporation of the
liquid (solid) above the same liquid (or solid) in a closed
container.
• The rate of evaporation is equal to the rate of
condensation
• Is it affected by
• Strength of intermolecular forces in the liquid?
• The stronger the IMFA, the lower the VP
• The weaker the IMFA, the higher the VP
• Temperature?
• Higher temperature increases energy to
overcome IMFA, higher VP
• Surface area of the container?
• VP is force/area
• The greater the surface area, more molecules
evaporate, the force increases proportionally
• No effect

22. Vapor Pressure Lowering
+ Non
Pure
Volatile Solution
Solvent
Solute

23. Vapor Pressure Lowering
• Evaporation occurs at the surface at any temperature
• Some of the non-volatile solute particles take the place
of the solvent particles at the surface
• Non-volatile solute particles increase the intermolecular
forces of attraction between solute and solvent
• Decreases the number of solvent particles evaporating
• Lower Vapor pressure for the solution

24. Raoult’s Law
• As the mole fraction of
the solvent increases,
the vapor pressure of the
solution approaches that
of the pure solvent.
• Dilute solutions have
properties closer to the
solvent

25. Raoult’s Law
• Nonvolatile solute • Volatile solute
• Volatile solvent • Volatile solvent
• No need to indicate
solvent/solute

26. Ideal vs. Non-ideal Solutions
• Does not follow • Does not follow
Raoult’s Law Raoult’s Law
• Follows Raoult’s Law
• Weak solute-solvent • Strong solute-solvent
• Non-polar/non-polar
interactions interactions
• Similar shape and size
• Both want to stay in • Both want to stay in
the vapor phase the liquid phase
• Predicted Ptotal is • Predicted Ptotal is lower
higher • Negatively deviating
• Positively Deviating • Predominantly polar
• Predominantly non- interactions
polar interactions

27. benzene toluene
acetone water
ethanol hexane

28. Summary of Solute-Solvent
Interactions in Solution
Deviation
Interactive Forces T for
from
Between Solute (A) and Hsoln Solution Example
Raoult’s
Solvent (B) Particles Formation
Law
None
Benzene-
A A, B B A B Zero Zero (ideal
toluene
solution)
Negative
A A, B B<A B Positive Negative Acetone-water
(exothermic)
Positive Ethanol-
A A, B B>A B Negative Positive
(endothermic) hexane

29. Boiling Point
 It is the temperature when the vapor pressure of
the liquid is equal to the prevailing atmospheric
pressure
 Is it affected by
◦ IMFA in liquid?
 Stronger IMFA, required more energy to increase VP, higher
BP
◦ Prevailing atmospheric pressure?
 Higher atmospheric pressure, higher BP
◦ Ground elevation?
 Higher ground elevation, lower atmospheric pressure, lower BP
◦ Prevailing temperature?
 Substance must reach a certain temperature before it boils
 Depends on the three previous factors

30. Boiling Point Elevation
+ Non Volatile
Pure Solvent /Nonelectrolyte Solution
Solute

31. Boiling Point Elevation
 Nonvolatile solute elevates the boiling point of the
solvent.
 ΔTb = Kbmsolute
ΔTb = boiling-point elevation
Kb = molal boiling-point elevation
constant
m = molality Boiling
Solvent
Normal of solution o
K , C/m
b
Point, oC
Water 100.0 0.512
Acetic acid (CH3COOH) 118.9 3.1
Benzene (C6H6) 80.1 2.53
Chloroform (CHCl3) 61.2 3.63

32. Freezing Point Depression
When a solute is dissolved in a solvent, the freezing point
of the solution is lower than that of the pure solvent.
ΔTf = Kfmsolute
ΔTf = freezing-point depression
Kf = molal freezing-point depression
constant
m = molality of solute
Normal Freezing
Solvent Kf, oC/m
Point, oC
Water 0 1.86
Ethyl ether (C4H10O) -116.2 1.79
Benzene (C6H6) 5.5 5.12
Chloroform (CHCl3) -63.5 4.70

33. Changes in BP and FP

34. Osmotic Pressure
Osmosis – flow of solvent into the solution through a
semipermeable membrane.
= MRT
= osmotic pressure (atm)
M = molarity of the solution
R = gas law constant
T = temperature (Kelvin)

37. Reverse Osmosis

38. Colligative Properties of
Electrolytes
van’t Hoff Factor, i
 The relationship between the moles of
solute dissolved and the moles of particles
in solution is usually expressed as:
moles of particles in solution
i =
moles of solute dissolved

39. Colligative Properties of
Electrolytes
Electrolyte i, (expected) i, (observed)
NaCl 1.9
MgCl2 2.7
MgSO4 1.3
i
FeCl3 3.4
HCl 1.9
Glucose* 1.0
Tb iK b m
Tf iK f m
iMRT

40. Ion Pairing
At a given instant a
small percentage of
the sodium and
chloride ions are
paired and thus count
• as a pairing is most important in concentrated solutions.
Ion single particle.
• As the solution becomes more dilute, the ions are farther
apart and less ion pairing occurs.
• Ion pairing occurs to some extent in all electrolyte solutions.
• Ion pairing is most important for highly charged ions.

41. Colloids
• A suspension of tiny particles in some medium.
• Tyndall effect – scattering of light by particles.
• Suspended particles are single large molecules or aggregates
of molecules or ions ranging in size from 1 to 1000 nm.

42. Colloids
Coagulation
 Destruction of a colloid.
 Usually accomplished either by heating or
by adding an electrolyte.