1. SOLUTIONS
A solution is a homogeneous mixture; particles are evenly distributed throughout the mixture.
Proportions may vary
Uniform ratio throughout the mixture
A liquid solution is clear. The particles are not visible, do not settle, and can not be filtered.
A solution differs from a suspension in that the particles of a suspension are visible, can be filtered, and settle.
A solution differs from a colloid in that the particles of a colloid exhibit Tyndall effect., yet do not settle.
(TYNDALL effect: the scattering of light by particles such as headlights in fog, flashlight through Jello or dilute milk)
A solution will not exhibit the Tyndall effect.

2. Cherry Kool-aid Red powder: flavor and color White crystals: sugar
Clear liquid: water
One substance dissolved in another
Solute: the substance being dissolved
Solvent: the substance that dissolves the solute
Sugar is the SOLUTE (smaller quantity)
Water is the SOLVENT (larger quantity)

3. Types of Solutions Gas (solvent is gas) Liquid (solvent is liquid)
Gas into Gas: air
Liquid into Gas: humidity
Solid into Gas: air pollution
Liquid (solvent is liquid)
Gas into Liquid: pop
Liquid into Liquid: vinegar
Solid into Liquid: sweet tea
Solid (solvent is solid)
Gas into Solid: absorbent charcoal
Liquid into Solid: dental fillings
Solid into Solid: alloys of metal

4. The Dissolving Process
Two factors affect the dissolving process: dissolution
The constant motion of the particles (There’s that good old kinetic molecular theory again!)
The polarity of the solute and solvent (Recall that polarity is when a compound has partial charges because of uneven distribution of charges)

5. Steps of the Dissolving Process
Moving solvent particles cluster around solute molecules or particles at the surface of the solid.
Solvent molecules pull solute off of the solid surface and into solution.
Moving solvent particles continue to spread solute evenly throughout the solution,
The process repeats itself as fresh layers of the solute are exposed.

6. Solvent particles cluster around solute particles at the surface.
Solvent particles pull solute particles away from surface, into solution.
Moving solute particles continue to spread solute evenly through solution.
MOLECULAR

7. Solvent particles cluster around solute particles at the surface.
Solvent particles pull solute particles away from surface, into solution.
Moving solute particles continue to spread solute evenly through solution.
IONIC

8. IONIC COMPOUNDS
When an ionic substance dissolves in water, the forces of the solvent pulling on the ions is stronger than the forces holding the ions together.
The ions separate. This is called DISSOCIATION
Because charged ions are present in an ionic solution, ionic solutions conduct electricity and are called ELECTROLYTES.
EXAMPLE: NaCl

9. MOLECULAR COMPOUNDS
Certain polar substances form ions when they dissolve in water. This process is called IONIZATION.
Because ions are formed, the solution conducts electricity.
These substance are also ELECTROLYTES.
EXAMPLE: HCl, HC2H3O2

10. MOLECULAR COMPOUNDS Other polar substances do not ionize in water.
Because ions are not formed, the solution does not conduct electricity.
These substances that do not ionize in water and do not conduct electricity are called NON-ELECTROLYTES.
EXAMPLE: sugar

11. ELECTROLYTES: substances that conduct electricity when dissolved in water
Ionic substances that separate into ions (dissociate) or polar molecular substances that form ions (ionization) when dissolved conduct electricity and are called ELECTROLYTES.

12. Review
A substance whose water solutions do not conduct electricity is a non- electrolyte.
Many covalent compounds
A substance that separates into ions (dissociates) or forms ions (ionizes) in a water solution conducts electricity and is called an electrolyte
All ionic and some covalent compounds

13. COMPOUNDS THAT DISSOLVE IN WATER ELECTROLYTES DO CONDUCT ELECTRICITY
IONIC COMPOUNDS DISSOCIATE INTO IONS
SOME POLAR MOLECULAR COMPOUNDS IONIZE
NON-ELECTROLYTES
DO NOT CONDUCT ELECTRICITY
OTHER POLAR MOLECULAR COMPOUNDS DISSOLVE WITH NO FORMATION OF IONS

14. The solute particles are less energetic than solvent
FACTORS THAT AFFECT THE RATE OF DISSOLUTION
Factors
Solid in Liquid
Gas in Liquid
TEMPERATURE
Temp >
Rate >
Rate <
AGITATION
Agitation >
Agitation >
SIZE OF PARTICLES
(surface area)
Size <
(surface area >) NA
PRESSURE
Pressure >
WHY?
(KMT)
The solute particles are less energetic than solvent
The solute particles are more energetic than solvent

15. Recall the Pop and Mentos experiment!
Think BIG
Recall the Pop and Mentos experiment!
The pop “explodes” because the dissolved gas rapidly leaves the solution because the candy gives it surfaces to collect on (nucleation sites).

16. Particles in Solutions
Solvents with non-polar molecules dissolve non-polar substances
Oil, grease, dry cleaning fluid, paint, turpentine
Solvents with polar molecules dissolve polar substances
Water dissolves sugar, ionic compounds
LIKE DISSOLVES LIKE

17. Terms Soluble: capable of being dissolved in a particular solvent
Insoluble: incapable of being dissolved in a particular solvent
Miscible: liquids that dissolve freely in any proportion
Immiscible: liquids that are not soluble in each other

18. Detergents and emulsifiers
Grease is non-polar
Water is polar
DETERGENT has
A non-polar end that dissolves the grease
A polar end that dissolves in the water to rinse it away
NONPOLAR DETERGENT POLAR
GREASE
WATER

21. CRAFTY CHEMISTRY
Artists use physical properties to create inspiring beauty!
ART and SCIENCE

22. Solubility
There are limits to the amount of solute that will dissolve in a given amount of solvent at a given temperature
There are some general terms:
Unsaturated
Saturated
Super-saturated

23. Unsaturated
a solution that can dissolve more of a given solute at a certain temperature
A crystal of solute added to an unsaturated solution will dissolve
When you add a second spoon of sugar to your cup of tea, it dissolves. The tea was an unsaturated solution.

24. Saturated
a solution that has dissolved all of the solute that it can at a certain temperature
A crystal of solute added to a saturated solution will drop to the bottom, un-dissolved.
When you add three spoons of sugar to your tea, some sugar drops to the bottom, undissolved. It is a saturated solution.
DYNAMIC EQUILIBRIUM exists:
changing but balanced.
Some solid dissolves, but as some dissolves, some re- crystallizes

25. Super-saturated
an unstable solution that contains more solute than a saturated solution at a certain temperature
A crystal of solute added to a super-saturated solution will cause crystallization. So will any disruption of the unstable solution.
Make a saturated solution at an elevated temperature and cool it slowly. At the lower temperature, the solute will remain dissolved in an unstable situation. If disrupted, the solute crystallizes.
Hot-packs and rock candy

28. SOLUBILITY CURVE
Max g of solute that will dissolve in 100 g of solvent at a given temperature

30. Solubility + Gas Laws = Safe SCUBA
Science of Diving

31. Concentration: the amount of solute in a given amount of solvent or solution
Dilute: a relatively small amount of solute in a relatively large amount of solvent
Concentrated: a relatively large amount of solute in a relatively small amount of solvent
We can do better!

32. Percent by volume mL of solute /100 mL of solution
3% hydrogen peroxide
3 mL H2O2 / 100 mL soln
70% isopropyl alcohol (what is different)
70 mL alcohol / 100 mL soln

33. Percent by mass g of solute/100 mL of solution IV saline
.9 g NaCl/100 mL solution x 100% = .9%
IV glucose
5 g glucose/100 mL soln x 100% = 5%

34. PPM and PPB
x/1,000,000
x/1,000,000,000
MAWC Annual Report to Consumers
Serial dilutions are often used
1x, 10x, 100x, 1000x, etc.
1 mL “neat” stock to 10 mL total volume = 10x
1 mL 10x to 10 mL total volume = 100x …

35. Mass per volume g solute/1000 mL solution 9 g NaCl/1000mL = 9 g NaCl/L
Not that useful to chemist…but MOLES are!
9 g NaCl | 1 mol NaCl = mol NaCl
1 L soln | g NaCl L soln
This helps chemists relate solutions to amounts in chemical reactions, and there is a word for this…

36. Molarity M = mol solute/liter of solution
Chemists use this because it lets us work concentration into stoichiometry problems
SEE EXAMPLE PROBLEMS

37. Molarity example 1
You have 3.50 L of solution that contains g of NaCl. What is the molarity?
M = mol/L

38. Molarity example 2
You have .8 L of a .5 M HCl solution. How many moles of HCl does this solution contain?
M = mol/L

39. Molarity example 3
To produce 40.0 g of silver chromate, you will need 23.4 g of potassium chromate in solution as a reactant. All you have on hand is 5 L of 6.0 M K2CrO4 solution. What volume of this solution is need to give you the 23.4 g K2CrO4 needed for this reaction?
M = mol/L

41. Molarity Practice
What is the molarity of a solution composed of 5.85 g of potassium iodide dissolved in enough water to make L of solution?
How many moles of H2SO4 are present in .500L of a .150 M H2SO4 solution?
What volume of 3.00 M NaCl is needed for a reaction that requires g NaCl?

42. QuikQuiz
What is the molarity of a solution of 80. g of NaOH dissolved in 1.0 L water?

43. 2 M = 2 moles per liter!

44. Molality m = mol solute/kg of solvent
Chemists sometimes use this because volume of liquids changes with temperature. Soon, we will be studying the effect of concentration as temperature changes.
SEE EXAMPLE PROBLEMS

46. Molality example 1
A solution was made by dissolving 17.1 g sucrose (molar mass g/mole) in 125 g water. What is the molal concentration of this solution (the molality)?
m = mol solute/ kg solvent

47. Molality example 2 m = mol solute/kg solvent
A solution of I2 in carbon tetrachloride, CCl4, is used for chemical tests for starch. How much iodine must be added to prepare a .480 m solution of iodine in CCl4 if g of CCl4 is used?
m = mol solute/kg solvent

48. Practice Molality
What is the molality of acetone in a solution composed of 225 g of acetone, C3H6O, dissolved in 200. g water?
What quantity, in grams, of methanol CH3OH, is required to prepare a .244 m solution in 400. g of water?

49. Moles before dilution = Moles after dilution
Dilutions: a concentrated solution is diluted by adding more solvent to get the desired concentration.
M1V = M2V2
Moles before dilution = Moles after dilution
M = molarity = mol/L
V = volume = L
M x V = mol/L x L = # mol of solute

50. Dilutions: a concentrated solution is diluted by adding more solvent to get the desired concentration.
The # of moles before dilution is equal to the # of moles after dilution. The same # of moles is present in more solvent. The concentration (M, molarity) changes, the volume (V) changes, but not the # of moles of solute (M x V).
Volume units may vary from L, but must be consistent within problem.
So, M1V1 = M2V2
SEE EXAMPLE PROBLEMS

51. Dilution example
I need 100. mL of 1.00 M HCl. I have a stock solution of 12.0 M HCl. Describe how to make the solution I need.
M1V1 = M2V2
1.00 M (100. mL ) = 12.0 M (x mL)
X = 8.33 mL 12 M HCl diluted to a total volume of 100. mL

52. Dilution Practice
How do you prepare 100 mL of .20 M HCl from a stock solution of 2.0 M HCl?
M1V1 = M2V2

53. Making solutions “Mass” the solid
Transfer solid to a small beaker/flask
Transfer all of solid by rinsing weighing paper with water
Swirl in small quantity of water
Transfer to volumetric flask with repeated rinses
Mix in small quantity of water
Fill carefully to the line
Cover with parafilm and mix thoroughly

54. Making dilutions
Measure quantity of stock solution using graduated cylinder or pipet
Transfer completely to volumetric flask with repeated rinses
Mix in water
Bring volume to line
Cover with parafilm and mix thoroughly