1. Why does a raw egg swell or shrink when placed in different solutions?
To play the movies and simulations included, view the presentation in Slide Show Mode.

2. Mixtures
Two or more substances (elements and/or compounds) combined but NOT chemically
each substance keeps its properties
Can be separated by physical properties
Example: salt, sand, and water

3. Heterogeneous mixture
“Not well mixed”; different parts
Parts can be easily separated
Salad

4. Homogeneous mixture “Well mixed”
So well mixed that parts are difficult to separate
Cake batter
Video Heterogeneous or homogeneous?

5. Colloids and Suspensions Types of Homogeneous mixtures
- Understanding Solutions
Colloids and Suspensions Types of Homogeneous mixtures
Colloids and suspensions are mixtures that have physical properties different from those of solutions.
Colloid: small undissolved particles that never settle (permanently suspended)
Suspension: particles settle out or can be filtered to separate

6. Some Definitions
A solution is a _______________ mixture of 2 or more substances in a single phase.
One constituent is usually regarded as the SOLVENT and the others as SOLUTES.

7. What Is a Solution?
Solutions can be made from any combinations of solids, liquids, and gases.

8. Parts of a Solution
SOLUTE – the part of a solution that is being dissolved (usually the lesser amount)
SOLVENT – the part of a solution that dissolves the solute (usually the greater amount)
Solute + Solvent = Solution
Solute
Solvent
Example
solid
liquid
gas

9. What Is a Solution? - Understanding Solutions
A solution has the same properties throughout at the molecular level. It contains solute particles (molecules or ions) that are too small to see.

10. Particles in a Solution
When a solution forms, particles of the solute leave each other and become surrounded by particles of the solvent.

12. Effects of Solutes on Solvents
At 0ºC, pure water freezes, but water mixed with a solute does not. Solutes lower the freezing point of a solvent.
Liquid water solution
Solid (frozen) water

13. Pure water boiling
Salt Water Boiling
Pure water boils at _______ degrees C?
Salt water boils at _______ degrees C.

14. Identifying Main Ideas
A solution is a well mixed mixture that contains a solvent and at least one solute.
Detail
Detail
Detail
Detail
The solvent is the substance present in the largest amount.
A solute is a substance present in a smaller amount than the solvent.
A solution has the same properties throughout.
A solution contains particles that are too small to see.

15. Net Ionic
Predict a reaction between lead (II) nitrate by precipitation with potassium iodide to determine if lead poisoning was the cause of death for a child who ate a toy produced in China.
The forensics scientist doesn’t have any potassium iodide, what could he use as an alternative that will cause a solid lead (II) iodide to form.

16. It’s suspected that a beverage has been tampered with by the addition of ice remover. These are typically made of sodium chloride, calcium chloride, magnesium chloride or a combination of the three salts. Using the solubility guidelines, create a strategy for adding reagents that would cause precipitation to determine which salt(s), if any, were in the beverage. Indicate whether any ion can’t be determined by precipitation.

17. Net Ionic Q
What is the net ionic equation for the precipitation of magnesium phosphate from the addition of magnesium nitrate to a sodium phosphate solution? Name 2 alternatives you could use.

18. Definitions Solutions can be classified as saturated or unsaturated.
A saturated solution contains the maximum quantity of solute that dissolves at that temperature.
An unsaturated solution contains less than the maximum amount of solute that can dissolve at a particular temperature

19. Example: Saturated and Unsaturated Fats
Saturated fats are called saturated because all of the bonds between the carbon atoms in a fat are single bonds. Thus, all the bonds on the carbon are occupied or “saturated” with hydrogen. These are stable and hard to decompose. The body can only use these for energy, and so the excess is stored. Thus, these should be avoided in diets. These are usually obtained from sheep and cattle fats. Butter and coconut oil are mostly saturated fats.
Unsaturated fats have at least one double bond between carbon atoms; monounsaturated means there is one double bond, polysaturated means there are more than one double bond. Thus, there are some bonds that can be broken, chemically changed, and used for a variety of purposes. These are REQUIRED to carry out many functions in the body. Fish oils (fats) are usually unsaturated. Game animals (chicken, deer) are usually less saturated, but not as much as fish. Olive and canola oil are monounsaturated.

20. Definitions
SUPERSATURATED SOLUTIONS contain more solute than is possible to be dissolved
Supersaturated solutions are unstable. The supersaturation is only temporary, and usually accomplished in one of two ways:
Warm the solvent so that it will dissolve more, then cool the solution
Evaporate some of the solvent carefully so that the solute does not solidify and come out of solution.

21. Kidney Stones
Urine volume plays a pivotal role in the process of stone formation. In particular, low volume, highly concentrated urine contributes to the supersaturation of elements normally found in the urine, such as calcium oxalate.  Fortunately, urine has the unique quality of holding more solute in suspension than does water and so can accept large concentrations of solute without precipitation. The ability of urine to keep such large concentrations in solution is, in part, due to the presence of protective organic molecules like citrate, as well as the presence of charged ions which alter the solubility (Menon & Resnick, 2002). Despite the fact that calcium oxalate can be present in urine in concentrations 7 to 11 times its solubility in water (Menon & Resnick, 2002), the point exists at which calcium oxalate exceeds the unique properties of urine; crystals will then form and possibly aggregate to form stones.

22. Supersaturated Sodium Acetate
One application of a supersaturated solution is the sodium acetate “heat pack.”

23. Practice Problems
Compounds Solubility (g/100 mL)
Sodium Cyanide (25 C) 48
Cadmium Cyanide (25 C) 1.7
Potassium Cyanide (25 C) 50
A mL solution contains 225 g of potassium cyanide. Is the solution saturated, unsaturated or supersaturated?
How many grams of sodium cyanide are needed to make 25 mL of the saturated solution?

24. IONIC COMPOUNDS Compounds in Aqueous Solution
Many reactions involve ionic compounds, especially reactions in water — aqueous solutions.
K+(aq) + MnO4-(aq)
KMnO4 in water
To play the movies and simulations included, view the presentation in Slide Show Mode.

25. Aqueous Solutions
How do we know ions are present in aqueous solutions?
The solutions can conduct electricity.
They are called ELECTROLYTES
HCl, MgCl2, and NaCl are strong electrolytes. They dissociate completely (or nearly so) into ions.

26. Aqueous Solutions
Some compounds dissolve in water but do not conduct electricity. They are called nonelectrolytes.
Examples include:
sugar
ethanol
ethylene glycol

27. It’s Time to Play Everyone’s Favorite Game Show… Electrolyte or Nonelectrolyte!

28. Conductivity Observations
Beaker
Contents
Conductivity Observations
Unknown 1
Unknown 2
Unknown 3
Water
(optional) Blank slide for in-class annotation during benchtop demonstration
Unknown 1 is a sugar solution, while Unknown 2 is a salt solution.
See facilitation guide for detailed notes

29. Which solution is which?
1 is sugar and 2 is salt
2 is sugar and 1 is salt
Both are sugar
Both are salt
What is 3?!
Correct answer: A
Representative results from pre-general chemistry: 78% correct
Note that this concept question could be asked after testing the unknown solutions, but before discussing water, tap water, etc.

30. Electrolytes and Nonelectrolytes
conduct electricity
substances that release ions when dissolved in water
This process is also called dissociation or ionization
Nonelectrolytes
substances that do NOT dissociate in water
do NOT conduct electricity
Ionic compounds (if they dissolve in water) are always electrolytes.
Most molecular compounds are nonelectrolytes.
Slide could be shown in class, or discussed and left for posted notes only.

31. If the atom-scale view of a compound in water looks like the picture on the right (II.), you might categorize the compound as… I.
II.
Correct answer: B
Representative results from pre-general chemistry: 81% correct (when used after sim demo with micro tab); 66% correct (when using prior to micro tab)
Follow-up discussion: Students were asked to explain what features they used in the pictures to decide on their answer
a. Ionic b. Molecular c. Neither

32. Ionic Compound Example
NaCl(s)  Na+(aq) + Cl- (aq)
Key facilitation notes:
Remember to annotate that (aq) stands for aqueous, i.e. dissolved in water, if students have not already been introduced to this notation
Structural features to highlight: repeat units (not individual molecules) AND the ratio for net neutral charge
Emphasize that solid NaCl already consists of ions, even though we don’t write the charges as part of the chemical formula (the ionic nature doesn’t go away just because of how we write it).
Key features of ionic solid:
Repeated units in larger lattice
Units are made of charged ions

33. Electrolytes in the Body
Carry messages to and from the brain as electrical signals
Maintain cellular function with the correct concentrations electrolytes
Make your own
50-70 g sugar
One liter of warm water
Pinch of salt
200ml of sugar free fruit squash
Mix, cool and drink

34. IONS
calcium – in bone and teeth. Also important for muscle contraction, blood clotting, and nerve function.
sodium – found outside the cell. Mainly involved in water balance as well as nerve signaling.
potassium – major cation inside the cell. Important for proper functioning of heart, muscles, kidneys, and nerves.
magnesium – in bone and cells. Involved in muscle, bone, nervous system, and takes part in many biochemical reactions.

35. Gatorade Sodium Citrate, Na3C6H5O7 Sucralose (Splenda), C12H19Cl3O8
Given the partial list of ingredients of a sports drink, which are electrolytes and which are non-electrolytes?
Water H2O
Sucrose Syrup, C12H22O11
Sodium Citrate,K3C6H5O7
Sodium Citrate, Na3C6H5O7
Sucralose (Splenda), C12H19Cl3O8

36. Concentration of Solute
The amount of solute in a solution is given by its concentration.
Molarity ( M ) =
moles solute
liters of solution

37. 1. 0 L of water was used to make 1. 0 L of solution
1.0 L of water was used to make 1.0 L of solution. Notice the water left over.

38. Step 1: Calculate moles of silver nitrate
PROBLEM: A sodium nitrate solution is used to develop fingerprints on porous objects, such as wood, by precipitating any chloride ions in the fingerprint. The solution is prepared by dissolving 30.0 g of silver nitrate in water to a final volume of 1.00 L. What is it’s Molarity?
Step 1: Calculate moles of silver nitrate
Step 2: Calculate Molarity
[AgNO3] = M

39. PROBLEM: Fingerprints that have been deposited in blood can be developed using an aqueous mixture with the dye amido black. One of the main ingredients is a citric acid solution prepared by dissolving 38.0 g of citric acid (C6H8O7) to a final volume of 2.00 L. What is the Molarity?
M C6H8O7

40. M=mol/V -> mol=M•V USING MOLARITY Calculate.
When the fingerprints in blood are on a painted surface that may be damaged by the traditional methanol-based solution, an alternative must be used with a M citric acid solution. Calculate the mass of citric acid to prepare 1.00 L of solution.
M=mol/V -> mol=M•V
Calculate.

41. 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

42. M1V1 = M2V2 Dilution of Solute
Changing the concentration of a solution by adding solvent.
M1V1 =
M2V2
initial
final

43. Step 1: Plug Step 2: And Chug
PROBLEM: A presumptitive test for LSD is the Ehrlich test that requires a 3.25 M HCL solution. Concentrated hydrochloric acid – the form in which most laboratories purchase HCl – is 12.1 M. If a mL sample of 3.25 M HCl is needed, how many mL of the concentrated HCl should be diluted?
Step 1: Plug
Step 2: And Chug

44. Step 1: Plug Step 2: And Chug
PROBLEM: A presumptive test is a quick, cheap test that indicates the drug of interest is most likely present. A confirmatory test is required to definitely prove the drug is present. For heroin, the presumptive test involves adding mercury (II) chloride solution, which forms a rosette of needle-shaped crystals if the heroin is present. The directions for preparing the solution call for 13.9 mL of a 1.00 M stock solution diluted to 75 mL. What is the final molarity of the mercury (II) chloride test solution?
Step 1: Plug
Step 2: And Chug

45. Concentration Units
An IDEAL SOLUTION is one where the properties depend only on the concentration of solute.
Need conc. units to tell us the number of solute particles per solvent particle.
The unit “molarity” does not do this! Volume changes with temperature and mass never changes!

46. Two Other Concentration Units
MOLALITY, m
m of solution =
mol solute
kilograms solvent
% by mass
grams solute
grams solution
% by mass =

47. Calculating Concentrations
Dissolve 62.1 g (1.00 mol) of ethylene glycol in 250. g of H2O. Calculate molality and % by mass of ethylene glycol.

48. Calculating Concentrations
Dissolve 62.1 g (1.00 mol) of ethylene glycol in 250. g of H2O. Calculate m & % of ethylene glycol (by mass).
Calculate molality
Calculate weight %

49. Learning Check
A solution contains 15 g Na2CO3 and 235 g of H2O? What is the mass % of the solution?
1) 15% Na2CO3
2) 6.4% Na2CO3
3) 6.0% Na2CO3

50. Using mass %
How many grams of NaCl are needed to prepare 250 g of a 10.0% (by mass) NaCl solution?

51. Try this molality problem
25.0 g of NaCl is dissolved in mL of water. Find the molality (m) of the resulting solution.
m = mol solute / kg solvent
25 g NaCl mol NaCl
58.5 g NaCl
= mol NaCl
Since the density of water is 1 g/mL, 5000 mL = 5000 g, which is 5 kg
0.427 mol NaCl
5 kg water
= m salt water

53. Colligative Properties
On adding a solute to a solvent, the properties of the solvent are modified.
Vapor pressure decreases
Melting point decreases
Boiling point increases
Osmosis is possible (osmotic pressure)
These changes are called COLLIGATIVE PROPERTIES.
They depend only on the NUMBER of solute particles relative to solvent particles, not on the KIND of solute particles.

54. Change in Boiling Point
Common Applications of Boiling Point Elevation

55. Why?
The density of water changes when something is added to it and Demerol has a density of g/mL. Analysis of a sample requires investigating physical properties.
Rubbing alcohol boils at 83C and water at 100C because of IMFs.
Vapor pressure is pressure exerted by molecules onto a liquid. Boiling happens when vapor pressure is equal to the pressure of the atmosphere.
When you add a solute the vapor pressure is lowered, so have to give even more E to make it equal to the external pressure.

56. Polluted Water Sample
It is suspected that a local mine has been polluting the river. A sample is sent to a lab to investigate it. If the BP of the sample matches that of regular water, does this mean that the sample has no pollution?
It’s likely, but the toxic substance could be extremely low levels that the BP is significantly changed or it could have evaporated from solution or decomposed. Need further testing!

58. Change in Freezing Point
Ethylene glycol/water
solution
Pure water
The freezing point of a solution is LOWER than that of the pure solvent

59. DYNAMITE!
Pure nitroglycerin is very sensitive to shock and can be detonated by dropping it or freezing.
Added ethylene glycol dinitrate which has a much lower freezing point.
Alfred Nobel created the Nobel Peace Prize because he felt badly about creating dynamite.
Equilibrium - Blocks part of the liquid solvent from interacting with molecules in the solid phase, but they can reenter the liquid phase. The solid molecules lose the sufficient energy to reenter that phase after a while so start to refreeze.

60. Change in Freezing Point
Common Applications of Freezing Point Depression
Ethylene glycol – deadly to small animals
Propylene glycol

61. Change in Freezing Point
Common Applications of Freezing Point Depression
Which would you use for the streets of Bloomington to lower the freezing point of ice and why? Would the temperature make any difference in your decision?
sand, SiO2
Rock salt, NaCl
Ice Melt, CaCl2

62. Boiling Point Elevation and Freezing Point Depression
∆T = K•m•i
i = van’t Hoff factor = number of particles produced per molecule/formula unit. For covalent compounds, i = 1. For ionic compounds, i = the number of ions present (both + and -)
Compound Theoretical Value of i
glycol 1
NaCl 2
CaCl2 3
Ca3(PO4)2 5

63. Boiling Point Elevation and Freezing Point Depression
∆T = K•m•i
m = molality
K = molal freezing point/boiling point constant
Substance Kf
benzene
5.12
camphor
40.
carbon tetrachloride
30.
ethyl ether
1.79
water
1.86
Substance Kb
benzene
2.53
camphor
5.95
carbon tetrachloride
5.03
ethyl ether
2.02
water
0.52

64. Change in Boiling Point
Dissolve 62.1 g of glycol (1.00 mol) in 250. g of water. What is the boiling point of the solution?
Kb = 0.52 oC/molal for water (see Kb table).
Solution ∆TBP = Kb • m • i
1. Calculate solution molality = 4.00 m
2. ∆TBP = Kb • m • i
∆TBP = oC/molal (4.00 molal) (1)
∆TBP = oC
BP = = oC (water normally boils at 100)

65. Freezing Point Depression
Calculate the Freezing Point of a 4.00 molal glycol/water solution.
Kf = 1.86 oC/molal (See Kf table)
Solution
∆TFP = Kf • m • i
= (1.86 oC/molal)(4.00 m)(1)
∆TFP = 7.44
FP = 0 – 7.44 = oC (because water normally freezes at 0)

66. Freezing Point Depression
At what temperature will a 5.4 molal solution of NaCl freeze?
Solution
∆TFP = Kf • m • i
∆TFP = (1.86 oC/molal) • 5.4 m • 2
∆TFP = oC
FP = 0 – 20.1 = oC

67. Preparing Solutions
Weigh out a solid solute and dissolve in a given quantity of solvent.
Dilute a concentrated solution to give one that is less concentrated.

68. ACID-BASE REACTIONS Titrations
H2C2O4(aq) NaOH(aq) --->
acid base
Na2C2O4(aq) H2O(liq)
Carry out this reaction using a TITRATION.
Oxalic acid,
H2C2O4

69. Setup for titrating an acid with a base

70. Titration 1. Add solution from the buret.
2. Reagent (base) reacts with compound (acid) in solution in the flask.
Indicator shows when exact stoichiometric reaction has occurred. (Acid = Base)
This is called NEUTRALIZATION.