1. Chapter 13 Solutions Cameroon: location of Lake Nyos
50 miles underneath lake Nyos CO2 is produced by molten volcanic rock (magma) and held in solution by the pressure of the water above it.

2. CHAPTER OUTLINE Type of Solutions Solubility & Saturation
Soluble & Insoluble Salts
Concentration Units
Dilution
Osmolarity
Tonicity of Solutions

3. Tragedy in Cameroon Lake Nyos
lake in Cameroon, West Africa
on August 22, 1986, > 1700 people & 3000 cattle died
Burped Carbon Dioxide Cloud Appeared From Nyos
CO2 seeps in from underground and dissolves in lake water to levels above normal saturation
though not toxic, CO2 is heavier than air – the people died from asphyxiation

4. Possible Resolution
scientists have studied Lake Nyos and similar lakes in the region to try and keep such tragedies from reoccurring
currently, they are trying to keep the CO2 levels in the lake water from reaching very high supersaturation levels by pumping air into the water to agitate it
By understanding solutions we are able to divert natural tragedies

5. TYPE OF SOLUTIONS
A solution is a homogeneous mixture of two substances:
Solute:
substance being dissolved
present in smaller amount
Solvent:
substance doing the dissolving
present in larger amount
Solutes and solvents may be of any form of matter: solid, liquid or gas.

6. Common Types of Solution
Solution Phase
Solute Phase
Solvent Phase
Example
gaseous solutions
gas
air (mostly N2 & O2)
liquid solutions
liquid
solid
soda (CO2 in H2O)
vodka (C2H5OH in H2O)
seawater (NaCl in H2O)
solid solutions
brass (Zn in Cu)

7. e.g. Brass (varies in composition)
Type
Color
% Cu
% Zn
Density
g/cm3 MP °C
Tensile
Strength
psi
Uses
Gilding
reddish 95 5
8.86
1066
50K
pre-83 pennies,
munitions, plaques
Commercial
bronze 90 10
8.80
1043
61K
door knobs,
grillwork
Jewelry
87.5
12.5
8.78
1035
66K
costume jewelry
Red
golden 85 15
8.75
1027
70K
electrical sockets,
fasteners & eyelets
Low
deep yellow 80 20
8.67
999
74K
musical instruments,
clock dials
Cartridge
yellow 70 30
8.47
954
76K
car radiator cores
Common 67 33
8.42
940
lamp fixtures,
bead chain
Muntz metal 60 40
8.39
904
nuts & bolts,
brazing rods

8. SOLUBILITY Like dissolves Like
Solutions form between solute and solvent molecules because of similarities between them.
Like dissolves Like
Ionic solids dissolve in water because the charged ions (polar) are attracted to the polar water molecules.
Non-polar molecules such as oil and grease dissolve in non-polar solvents such as kerosene.

9. SOLUBILITY
solutions that contain metal solutes and a metal solvent are called alloys
when one substance (solute) dissolves in another (solvent) it is said to be soluble
salt is soluble in water,
bromine is soluble in methylene chloride
chlorocarbon that is not miscible with water,
but will dissolve in most organic solvents
when one substance does not dissolve in another it is said to be insoluble
oil is insoluble in water

10. Salt Dissolving in Water
partial + surround the anion
partial – surround the cation
Solvation is the process of attraction and association of molecules of a solvent with molecules or ions of a solute. As ions dissolve in a solvent they spread out and become surrounded by solvent molecules.

11. SOLUBILITY
there is usually a limit to the solubility of one substance in another
gases are always soluble in each other
two liquids that are mutually soluble are said to be miscible
alcohol and water are miscible
oil and water are immiscible

12. Descriptions of Solubility
saturated solutions have the maximum amount of solute that will dissolve in that solvent at that temperature
unsaturated solutions can dissolve more solute
supersaturated solutions are holding more solute than they should be able to at that temperature
unstable

13. Adding Solute to various Solutions
unsaturated
saturated
supersaturated

14. Supersaturated Solution
A supersaturated solution has more dissolved solute than
the solvent can hold. When disturbed, all the solute above
the saturation level comes out of solution.

15. Electrolytes
electrolytes are substances whose aqueous solution is a conductor of electricity
strong electrolytes, all the electrolyte molecules are dissociated into ions, SALTS
nonelectrolytes, none of the molecules are dissociated into ions, SUGARS
weak electrolytes, a small percentage of the molecules are dissociated into ions

16. SOLUBILITY
Solubility refers to the maximum amount of solute that can be dissolved in a given amount of solvent.
Many factors affect the solubility of a solute in a solution.
Type of solute
Type of solvent
Temperature
Solubility is measured in grams of solute per 100 grams of solvent at a given temperature.

17. SOLUBILITY
Solubility of most solids in water increases as temperature increases.
Using a solubility chart, the solubility of a solute at a given temperature can be determined.
For example, KNO3 has a solubility of 80 g/100 g H2O (80%) at 40 C.

18. SOLUBILITY
OF GASES
Solubility of gases in water decreases as temperature increases.
At higher temperatures more gas molecules have the energy to escape from solution.
Henry’s law states that the solubility of a gas is directly proportional to the pressure above the liquid.
For example, a can of soda is carbonated at high pressures in order to increase the solubility of CO2. Once the can is opened, the pressure is reduced and the excess gas escapes from the solution.

19. Solubility and Pressure
the solubility of gases in water depends on the pressure of the gas
higher pressure = higher solubility
lower pressure
above the soln
higher pressure
above the soln
less gas
in soln
more gas
in soln

20. Solubility and Pressure
When soda pop is sealed, the CO2 is under pressure.
Opening the container lowers the pressure, which decreases
the solubility of CO2 and causes bubbles to form.

21. Solution Concentration
dilute solutions have low solute concentrations
concentrated solutions have high solute concentrations

22. CONCENTRATION UNITS amount of solute Concentration =
The amount of solute dissolved in a certain amount of solution (occasionally amount of solvent) is called concentration.
amount of solute
Concentration =
amount of solution
Three types of concentration units will be studied in this class:
Mass Percent:
(m/m) and (m/v)
Molarity

23. mass of solute + mass of solvent
MASS PERCENT
Mass percent (% m/m) is defined as the mass of solute divided by the mass of solution.
mass of solute + mass of solvent

24. MASS/VOLUME PERCENT
Mass/Volume percent (% m/v) is defined as the mass of solute divided by the volume of solution.

25. Example 1:
What is the mass % (m/m) of a NaOH solution that is made by dissolving 30.0 g of NaOH in g of water?
Mass of solution =
30.0 g g
= g

26. Example 2:
What is the mass % (m/v) of a solution prepared by dissolving 5.0 g of KI to give a final volume of 250 mL?

27. USING PERCENT CONCENTRATION
Some examples of percent compositions, their meanings, and possible conversion factors are shown in the table below:
In the preparation of solutions, one often needs to calculate the amount of solute or solution.
To achieve this, percent composition can be used as a conversion factor.

28. Example 1: 1.0 g Clindamycin 65 mL solution x = 0.65 g 100 mL solution
A topical antibiotic solution is 1.0% (m/v) Clindamycin. How many grams of Clindamycin are in 65 mL of this solution?
1.0 g Clindamycin
100 mL solution
65 mL solution x
= 0.65 g

29. Example 2: 40.0 g LiNO3 150 mL solution x = 60. g LiNO3
How many grams of solute are needed to prepare 150 mL of a 40.0% (m/v) solution of LiNO3?
40.0 g LiNO3
100 mL solution
150 mL solution x
= 60. g LiNO3

30. MOLARITY
The most common unit of concentration used in the laboratory is molarity (M).
Molarity is defined as:
moles of solute
Molarity =
Liter of solution

31. Example 1:
What is the molarity of a solution containing 1.4 mol of acetic acid in 250 mL of solution?
Vol. of solution =
= 5.6 M
Molarity =

32. Example 2:
What is the molarity of a solution that contains 75 g of KNO3 in 350 mL of solution?
Mol of solute =
= 0.74 mol
Vol of solvent =

33. Preparing a 1.00 M NaCl Solution
Weigh out
1 mole (58.45 g)
of NaCl and add
it to a 1.00 L
volumetric flask.
Step 1
Step 2
Add water to
dissolve the
NaCl, then
add water to
the mark.
Step 3
Swirl to Mix

34. Moles solute = Molarity x volume
USING MOLARITY
Molarity relationship can be used to calculate:
Amount of solute:
Moles solute = Molarity x volume
Volume of solution:

35. Example 1: Vol. of solution = 16 1 mol of solute = = 5.2 mol
How many moles of nitric acid are in 325 mL of 16 M HNO3 solution?
Vol. of solution = 16 1
mol of solute =
= 5.2 mol

36. Example 2: Vol. of solution = 4.50 1 mol of solute = = 1.46 mol
How many grams of NaHCO3 are in 325 mL of 4.50 M solution of NaHCO3?
Vol. of solution =
4.50 1
mol of solute =
= 1.46 mol
= 123 g
mass of solute =

37. Example 3: mol of solute = = 0.500 mol 1 2.0 Vol. In L = = 0.25 L
What volume (mL) of 2.0 M NaOH solution contains 20.0 g of NaOH?
mol of solute =
= mol 1
2.0
Vol. In L =
= 0.25 L
Vol. In mL =
= 250 mL

38. Example 4: mol of solute = = 0.0555 mol 1 0.300 Vol. In L = = 0.185 L
How many mL of a M glucose (C6H12O6) IV solution is needed to deliver 10.0 g of glucose to the patient?
mol of solute =
= mol 1
0.300
Vol. In L =
= L
Vol. In mL =
= 185 mL

39. DILUTION When more water is added to a solution,
Amount of solute remains constant
When more water is added to a solution,
Solutions are often prepared from more concentrated ones by adding water. This process is called dilution.
Volume and concentration are inversely proportional
Volume increases
Concentration decreases
Frozen juice
Diluted juice
Water

40. Concentrated solution
DILUTION
The amount of solute depends on the concentration and the volume of the solution.
Therefore,
M1 x V1 = M2 x V2
Concentrated solution
Dilute solution

41. Concentration decreases
Example 1:
Concentration decreases
What is the molarity of the final solution when 75 mL of 6.0 M KCl solution is diluted to 150 mL?
Volume increases
M1 x V1 = M2 x V2
M1 = 6.0 M
V1 = 75 mL
M2 = ???
V2 = 150 mL
M2 = 3.0 M

42. Concentration decreases
Example 2:
Volume increases
What volume (mL) of 0.20 M HCl solution can be prepared by diluting 50.0 mL of 1.0 M HCl?
Concentration decreases
M1 x V1 = M2 x V2
M1 = 1.0 M
V1 = 50.0 mL
M2 = 0.20 M
V2 = ???
V2 = 250 mL

43. Making a Solution by Dilution
M1 x V1 = M2 x V2
M1 = 12.0 M V1 = ? L
M2 = 1.50 M V2 = 5.00 L
dilute L of 12.0 M solution to 5.00 L

44. Solution Stoichiometry
we know that the balanced chemical equation tells us the relationship between moles of reactants and products in a reaction
2 H2(g) + O2(g) → 2 H2O(l) implies for every 2 moles of H2 used, you need 1 mole of O2 and to make 2 moles of H2O
molarity is the relationship between moles of solute and liters of solution, thus we can measure the moles of a material in a reaction within a solution by knowing its molarity and volume

45. 2 KI(aq) + Pb(NO3)2(aq) → PbI2(s) + 2 KNO3(aq)
Example 1:
How much M KI solution, in liters, is required to completely precipitate all the Pb2+ in L of M Pb(NO3)2?
2 KI(aq) + Pb(NO3)2(aq) → PbI2(s) + 2 KNO3(aq)
Identify what the question is looking for:
volume of KI solution, L
0.115 M KI  mol KI  1 L solution
0.225 M Pb(NO3)2  mol Pb(NO3)2  1 L solution
Chem. Eq’n  2 mol KI  1 mol Pb(NO3)2

46. = L
= L

47. OSMOLARITY
Recall that when ionic substances (strong electrolytes) dissolve in water they form several particles for each formula unit.
For example:
Many important properties of solutions depend on the number of particles formed in solution.
NaCl (s)
Na+ (aq) + Cl (aq)
1 formula unit
2 particles

48. OSMOLARITY
CaCl2 (s)
Ca2+ (aq) + 2 Cl (aq)
3 particles
1 formula unit

49. OSMOLARITY
When covalent substances (non- or weak electrolytes) dissolve in water they form only one particle for each formula unit.
For example:
C12H22O11 (s)
C12H22O11 (aq)
1 formula unit
1 particle

50. Number of particles in solution
OSMOLARITY
Osmolarity of a solution is its molarity multiplied by the number of particles formed in solution.
Osmolarity = i x Molarity
Number of particles in solution

51. Same molarities but different osmolarities
Examples:
1 particle in solution
0.10 M NaCl =
2 x 0.10 M =
0.20 osmol
0.10 M CaCl2 =
3 x 0.10 M =
0.30 osmol
2 particles in solution
0.10 M C12H22O11 =
1 x 0.10 M =
0.10 osmol
3 particles in solution
Same molarities but different osmolarities

52. TONICITY OF SOLUTIONS
Because the cell membranes in biological systems are semipermeable, particles of solute in solutions can travel in and out of the membranes. This process is called osmosis.
The direction of the flow of solutions in or out of the cell membranes is determined by the relative osmolarity of the cell and the solution.
The comparison of osmolarity of a solution with those in body fluids determines the tonicity of a solution.

53. ISOTONIC SOLUTIONS
Solutions with the same osmolarity as the cells (0.30) are called isotonic.
These solutions are called physiological solutions and allow red blood cells to retain their normal volume.

54. HYPOTONIC SOLUTIONS
Solutions with lower osmolarity than the cells are called hypotonic.
In these solutions, water flows into a red blood cell, causing it to swell and burst (hemolysis).

55. HYPERTONIC SOLUTIONS
Solutions with greater osmolarity than the cells are called hypertonic.
In these solutions, water leaves the red blood cells causing it to shrink (crenation).

56. Examples: 0.10 M NaCl = 0.20 osmol hypotonic 0.10 M CaCl2 = 0.30 osmol
isotonic
0.10 M C12H22O11 =
0.10 osmol
hypotonic

57. THE END