1. Solutions

2. Composition
solute
solvent
dilute
concentrated

3. Composition Molarity (M)— the number of moles of solute per liter of
solution
mol/L

4. Composition Mass percent— the mass of solute per
mass of solution x 100
unit-less

5. Composition Mole fraction ()— the moles of solute per
total moles of solution
(solute) or the moles of
solvent per total moles
of solution (solvent)

6. Composition Molality (m)— the moles of solute per kilogram of solvent
mol/kg

7. Composition Normality (N)— the equivalents of solute
per liter of solution
eq/L

8. Composition Equivalent— the mass of an acid or
base that can furnish or
react with 1 mole of
protons

9. Composition Equivalent— the mass of an oxidizing
or reducing agent that
can accept or furnish 1
mole of electrons

10. Composition Practice
Mylanta® Liquid contains
200mg of aluminum
hydroxide for every 5mL
of solution.

11. Composition Practice
Assuming that the
aluminum hydroxide is
the only ingredient,
what is the molarity of
the solution?

12. Composition Practice
2. Assuming that the
density of the solution
is 1g/mL, what is the
mass percent of the
solution?

13. Composition Practice
3. Assuming that the
mass of water is
4800mg, what are the
mole fractions of both
the solute and the
solvent?

14. Composition Practice
4. What is the molality
of the solution?
What is the
normality of the
solution?

15. 0.513 mol/L
4% (mass)
= solute
0.990 = solvent
0.534 mol/kg
1.538 eq/L

16. Energy of Solution Formation
“like dissolves like”
due to the energy associated with the formation of a solution
Step 1: solute expands (endo)
Step 2: solvent expands (endo)
Step 3: solute and solvent interact (usually exo)

17. Hsoln= H1 + H2 + H3 sum of steps 1-3 gives the
Energy of Solution Formation
sum of steps 1-3 gives the
enthalpy of solution, or heat
of solution (Hsoln)
Hsoln= H1 + H2 + H3

18. Energy of Solution Formation
Consider mixing oil and water…
They are immiscible.
Oil molecules are large and
have LDF…thus, H1 will be
large and positive for the
oil expansion

19. Energy of Solution Formation
Water molecules have
H-bonds…thus, H2 will be
large and positive for the
water expansion

20. Energy of Solution Formation
H3 will be small since
nonpolar and polar molecules
tend to have no attractive
forces

21. Energy of Solution Formation
Hsoln will be large and positive
because of the large impact
that H1 and H2 have.
Thus, it would require a large
amount of energy for the oil
and water to mix

22. Energy of Solution Formation
Consider mixing NaCl and
water…
They are soluble.
NaCl formula units have
strong ionic forces…thus,
H1 will be large and positive
for the NaCl expansion

23. Energy of Solution Formation
Again, water molecules have
H-bonds…thus, H2 will be
large and positive for the
water expansion

24. Energy of Solution Formation
H3 will be large and
negative since the attractive
forces between the ions and
the polar water molecules
are so strong

25. Energy of Solution Formation
The Hsoln for NaCl in water
is actually 3 kJ/mol. It is
positive and small…and it is
more disordered than the
original NaCl and water…
hence, favorable.

26. Solubility
the amount of solute that dissolves in solvent

27. Factors Affecting Solubility
Structure
Pressure
Temperature

28. Structure’s Effect
A, D, E, & K are fat-soluble because nonpolar, long H-C chains (hydrophobic)
B & C are water-soluble because they have polar
0-H and C-O bonds (hydrophilic)

29. Pressure’s Effect
Gas in a liquid
Increased pressure above a liquid means increased solubility of a gas in the liquid…Henry’s Law

30. Henry’s Law
Amount of a gas dissolved in solution is directly proportional to the pressure of the gas above the solution.

31. Henry’s Law
P = kC
S1 = S2
P1 P2
Obeyed particularly well in non-dissociated solutions

32. Temperature’s Effect
Most solids’ solubilities will increase as temperature is increased…but not all
Must be determined by experimentation

33. Temperature’s Effect
Na2SO4
Na2SO4

34. Temperature’s Effect
Gases’ solubilities will decrease as temperature is increased
Thermal pollution

35. Lake Nyos, Cameroon

36. Lake Nyos, Cameroon
August 21, 1986
>1700 people and >3000 cattle killed
Lake turn-over thought to have been caused by volcanic activity

37. Lake Nyos, Cameroon

38. Vapor Pressure
decreases with the addition of a nonvolatile solute to a solvent
François Raoult studied the effects of a solute on vapor pressure

39. Psoln = (Posolvent)(solvent) Linear relationship y = mx + b
Raoult’s Law
Psoln = (Posolvent)(solvent)
Linear relationship
y = mx + b
b is zero

40. solvent is the mole fraction of the solvent
Raoult’s Law
Psoln is the vapor pressure of the solution
Posolvent is the vapor pressure of the pure solvent
solvent is the mole fraction of the solvent

41. For volatile solutions, Ptotal = (PoA)(A) + (PoB)(B)
Raoult’s Law
For volatile solutions,
Ptotal = (PoA)(A) + (PoB)(B)

42. Raoult’s Law
is to solutions what the ideal gas law is to gases
Strong solute-solvent attraction results in a vapor pressure lower than what Raoult’s Law predicts

43. 6. A carbonated beverage is bottled at 25°C with 5
6. A carbonated beverage is bottled at 25°C with 5.00atm over the CO2 in the liquid. Assuming that the partial pressure of the CO2 in the atmosphere is

44. 0.0004atm, calculate the
equilibrium concentrations
of CO2 before and after
the bottle is opened. The
Henry’s Law constant for
CO2 is 32Latm/mol at
25°C

45. 7. A solution was prepared by adding 20
7. A solution was prepared by adding 20.0g of urea to 125g water at 25°C, the temperature at which water’s vapor pressure is 23.76torr. The

46. observed vapor pressure
of the solution was found
to be 22.67torr. What is
the molar mass of urea?

47. 8. A solution is prepared by mixing 5. 81g acetone (C3H6O) and 11
8. A solution is prepared by mixing 5.81g acetone (C3H6O) and 11.9g chloroform (CHCl3). At 35°C this solution has a total vapor pressure of 260torr.

48. Is this an ideal solution?
The vapor pressures of
pure acetone and
chloroform at 35°C are
345 and 293torr,
respectively.

49. The unopened bottle’s CO2 concentration is 0. 160 mol/L
The unopened bottle’s CO2 concentration is mol/L. The opened bottle’s concentration is
1.2 x 10-5 mol/L. That’s why it tastes flat.

50. 7. The molar mass of urea is 59.7 g/mol.
8. The expected Ptotal is 319torr. Since Ptotal is actually 260torr, the solution does not behave ideally.

51. Colligative Properties
are dependent upon the number of solute particles dissolved in solution
Boiling point
Freezing point
Osmotic pressure

52. Boiling Point
is the temperature at which a substance’s vapor pressure equals the atmospheric pressure
What effect does the addition of a nonvolatile solute have on vapor pressure?

53. Tb = kbmsolutei Boiling Point
Thus, the boiling point of a solvent is elevated when a nonvolatile solute is added.
The amount by which it increases is calculated by…
Tb = kbmsolutei

54. Boiling Point Tb is the change in boiling point of the solution
kb is the boiling point constant for the solvent
msolute is the molality of the solute
i is the van’t Hoff factor

55. van’t Hoff factor Boiling Point
the number of particles of dissolved solute per mole of solute…in other words, the number of dissociated particles

56. Know the boiling and point constant for water…
Boiling Point
Know the boiling and point constant for water…
kb = 0.512°Ckg/mol

57. Freezing Point
is the temperature at which a solid’s vapor pressure equals its liquid’s vapor pressure
A nonvolatile solute will lower the vapor pressure of the liquid.

58. Freezing Point
As the solution is cooled the vapor pressure of the pure solid decreases more rapidly than the vapor pressure of the pure liquid.
Thus, the freezing point will be lowered.

59. Know the freezing point constant for water…
Tf = kfmsolutei
Know the freezing point constant for water…
kf = 1.86°Ckg/mol

60.  = MRTi Osmotic Pressure
is the pressure needed to stop osmosis from occurring
may be calculated using
 = MRTi

61.  is the osmotic pressure M is the molarity of the solution
Osmotic Presure
 is the osmotic pressure
M is the molarity of the solution
R is the gas law constant, Latm/Kmol
T is the Kelvin temperature

62. When pressure greater than  is applied, reverse osmosis will occur
Osmotic Presure
When pressure greater than  is applied, reverse osmosis will occur
Solute particles are filtered out
Desalination is an example

63. Isotonic solutions Hypertonic solutions Hypotonic solutions
same osmotic pressure
Hypertonic solutions
migration of solvent out of cells results in crenation
Hypotonic solutions
migration of solvent into cells results in hemolysis

64. 9. My car’s cooling system contains 2. 51kg of water and 2
9. My car’s cooling system contains 2.51kg of water and 2.45kg of ethylene glycol (antifreeze), C2H6O2. Below what temperature will my engine block freeze?

65. 10. If I were to substitute the ethylene glycol with sodium chloride, below what temperature will my engine block freeze?

66. 11. When 10. 0g of camphor are added to 100g of benzene, Tob is 80
11. When 10.0g of camphor are added to 100g of benzene, Tob is 80.1°C and kb is 2.53 °Ckg/mol, the boiling point of the solution is 81.76°C. What is the molar mass of the camphor?

67. 12. A 20. 0-mg sample of a protein is dissolved in water to make 25
12. A 20.0-mg sample of a protein is dissolved in water to make 25.0mL of solution. The osmotic pressure of the solution is 0.56torr at 25°C. What is the molar mass of the protein?

68. -29.2 °C
-62.1 °C
152g/mol
26550g/mol