1. Solutions
How can one differentiate between saturated, unsaturated, and supersaturated solutions?

2. Definition of Solution
A homogeneous mixture of a solute dissolved in a solvent.
Solute: the substance being dissolved, or the substance in lesser amount
Solvent: the medium in which the solute is dissolved, or the substance in greater amount
WATER
is a common solvent

3. Solutions can be formed from combinations of the different phases
Solid in a liquid: Salt water
Gas in a liquid: Soda
Gas in a gas: Air
Liquid in Liquid: Rubbing Alcohol

4. Properties of Aqueous (Water-Based) Solutions
Solute particles do not settle
Solute and solvent will pass through a filter
Solutions can be colored but are always clear
Do not disperse light (particles are too small)

5. “Like Dissolves Like” Water is a polar molecule
Other polar molecules and ionic compounds can typically dissolve well in water
Non-polar molecules cannot dissolve well in water
Non-polar molecules dissolve well in non-polar solvents (like benzene, C6H6, or carbon tetrachloride, CCl4)

6. Molecule – Ion Attraction
Like an intermolecular force of attraction
In water, many ionic substances break apart
Positive ions are attracted to the partial negative oxygen atoms of water
Negative ions are attracted to the partial positive hydrogen atoms of water

7. Solubility
Describes how much of a solute can be dissolved in a solvent
Depends on temperature, pressure, and the chemical nature of substances
Solids in water: as temp. increases, solubility generally increases.
Gases in water: as temp. increases, solubility decreases.

8. Solubility
Changes in pressure do not affect the solubility of a solid in a liquid
As pressure increases, the solubility of a gas in a liquid increases
Under what conditions of temperature and pressure is a gas most soluble?
Think About Soda!

9. Types of Solutions Saturated
contains the maximum amount of solute allowed under the given conditions
If the solute is a solid, one more added crystal will not dissolve
“on the curve” (Table G)

10. Types of Solutions Unsaturated
contains less than the maximum amount of solute allowed under the given conditions (more can dissolve)
Ex. Watered down Kool-Aid
If the solute is a solid, one more added crystal will dissolve
“below the curve” (Table G)

11. Types of Solutions Supersaturated
contains more than the maximum amount of solute allowed under the given conditions
Ex. Honey and solutions used for making rock candy
If the solute is a solid, one more added crystal will cause other solute particles to come out of solution (sometimes rapidly)
“above the curve” (Table G)

12. Comparing Different Solutions
The words concentrated and dilute are relative terms used to describe solutions
A solution that is “concentrated” has a relatively large amount of solute per unit solvent
A solution that is “dilute” has a relatively small amount of solute per unit solvent

13. Table G: Solubility Curves
What type of solution is created by adding 25g of NaCl in 100g of water at 30ºC?
How many more grams of NaCl are needed to make the solution saturated?

14. Table G: Solubility Curves
How many grams of NH4Cl can dissolve in 100g of water at 85ºC? How many in 200g of water? 50g of water?
What is more soluble in water at 50ºC? NaNO3 or KNO3? At what temperature is the solubility the same?

15. Table G: Solubility Curves
Which is more soluble at 70ºC? NaCl or KClO3?
Which is less soluble at 25ºC? HCl or NH3?

16. Table F: Solubility Guidelines

17. Table F: Solubility Guidelines
Predict the solubility:
NaCl
NH4Br
Ca(NO3)2
AgCl
CuSO4
BaSO4

18. Table F: Solubility Guidelines
Predict the solubility:
Na2CO3
(NH4)3PO4
BaCrO4
MgS
KOH
Zn(OH)2

19. Double Replacement Reactions
Predict whether or not a precipitate will form:
CuSO4(aq) + Na2CO3(aq)  ?

20. Complete Ionic Equation
Double Replacement Reactions
Complete Ionic Equation
First, break apart the reactants as individuals ions
Then, break apart the soluble (aqueous) products as individual ions
Do not break apart insoluble (solid) products or liquid and gaseous products
Cu+2(aq) + SO4-2(aq) + 2 Na+(aq) + CO3-2(aq) Na+(aq) + SO4-2(aq) + CuCO3(s)
(Write it all together in one line)
Cu+2(aq) + SO4-2(aq) + 2 Na+(aq) + CO3-2(aq)2 Na+(aq) + SO4-2(aq) + CuCO3(s)

21. Double Replacement Reactions
Spectator Ions
Ions that do not participate in a reaction
Appear the same on both sides of the equation
Cu+2(aq) + SO4-2(aq) + 2 Na+(aq) + CO3-2(aq)2 Na+(aq) + SO4-2(aq) + CuCO3(s)
Na+(aq) and SO4-2(aq) are spectator ions

22. Double Replacement Reactions
Net Ionic Equation
The balanced equation without spectator ions
Remove the ions that appear the same on both sides of the equation
Cu+2(aq) + SO4-2(aq) + 2 Na+(aq) + CO3-2(aq)2 Na+(aq) + SO4-2(aq) + CuCO3(s)
Cu+2(aq) + CO3-2(aq)  CuCO3(s)

23. Concentrations
Mathematical way to describe the amount of solute in a particular solution

24. Comparing Different Solutions
The words concentrated and dilute are relative terms used to describe solutions
A solution that is “concentrated” has a relatively large value of concentration
A solution that is “dilute” has a relatively small value of concentration
Which solution is more concentrated?
1 M NaCl or 2 M NaCl

25. Comparing Different Solutions
The words concentrated and dilute are relative terms used to describe solutions
A solution that is “concentrated” has a relatively large value of concentration
A solution that is “dilute” has a relatively small value of concentration
Which solution is more dilute?
0.5 M HCl or 3 M HCl

26. Molarity (M) M is the same as mol/L
Three forms of the equation:
moles of solute
Molarity =
liters of solution
moles of solute =
Molarity x liters of solution
moles of solute
liters of solution =
Molarity

27. Molarity Example Problems
What is the molarity of a solution if 3.0 moles of HCl are dissolved in enough water to make 750mL of a solution?
moles of solute
Molarity =
liters of solution
3.0 moles
= 4.0 M
Molarity =
0.75 L

28. Molarity Example Problems
How many moles of KCl are required to make 240mL of a solution that has a concentration of 0.50 M?
moles of solute =
Molarity x liters of solution
moles of solute =
0.50 mol/L x 0.24L
= 0.12 mol

29. Molarity Example Problems
How many liters of a 2.0 M solution can one create with 6.0 moles of NaCl?
moles of solute
liters of solution =
Molarity
6.0 mol
liters of solution =
= 3.0 L
2.0 mol/L

30. Molarity Example Problems
What is the molarity of a solution if 120.g of NaOH are dissolved in enough water to make 750mL of a solution?
1 mol
120.g x
= 3.00 mol
40.0 g
moles of solute
Molarity =
liters of solution
3.00 moles
= 4.0 M
Molarity =
0.75 L

31. Molarity Example Problems
How many grams of CuSO4 are required to make 350. mL of a solution that has a concentration of 2.00 M?
moles of solute =
Molarity x liters of solution
moles of solute =
2.00 mol/L x L
159.6 g
= mol x
= 112 g
1 mol

32. Making a Solution Correctly
How does one correctly prepare 500.mL of a 3.00M solution of NaOH?
First determine the number of moles needed:
moles of solute =
Molarity x liters of solution
moles of solute =
3.00M x 0.500L
= 1.50mol
Then determine the mass of NaOH needed
40.0 g
1.50 mol NaOH x
= 60.0 g NaOH
1 mol

33. Making a Solution Correctly
How does one correctly prepare 500.mL of a 3.00M solution of NaOH?
Use a volumetric flask to create the solution:
First add the 60.0 g NaOH to the flask with enough water to dissolve the solid completely
Then add more water to the flask to bring the final volume of the solution to exactly 500.mL

34. Dilution Problems:
If a solution is diluted with the addition of water, the new solution will have the same number of moles of solute particles as the original solution.
AND
moles of solute =
Molarity x liters of solution
SO….
M1V1 = M2V2

35. Dilution Example Problem
If a 4.00M solution of NaOH that has an original volume of 125mL is diluted with water to have a final volume of 1.000L, what is the molarity of the new solution?
M1V1 = M2V2
M1V1
4.00M x 0.125L
M2 = = V2
1.000L
0.500M

36. Dilution Example Problem
A 1.50M solution of NaCl has an original volume of 500.mL. It is allowed to sit open to air so that some of the water evaporates. If the new volume is 250.mL, what is the molarity of the new solution?
M1V1 = M2V2
M1V1
1.50M x 500.mL
M2 = = V2
250.mL
3.00M

37. Dilution Example Problem
How much water would one need to add to 150.mL of a 12.0M solution of HCl to make a solution that has a concentration of 3.00M?
First determine the new volume of the solution:
M1V1
12.0M x 150.mL
V2 = =
= 600.mL M2
3.00M
Then determine how much water one needs:
150.mL + x = 600.mL
= 450.mL

38. Percent Solution by Mass
mass of solute
x 100
% Solution by Mass =
mass of solution
What is the percent by mass of a solution that has a total mass of 84 g and the mass of the solute is 21 g?
25 %

39. Percent Solution by Mass
mass of solute
x 100
% Solution by Mass =
mass of solution
How many grams of the solute KCl are there in a solution that has a concentration of 16% by mass and a total mass of 250.g?
Convert 16% to a decimal 
0.16
mass of solute = 0.16 x 250.g
= 40.g

40. More Challenging… 35 g x 100 % Solution by Mass = 35 g + 140.g
What is the percent by mass of an aqueous solution of NaCl if 35g of NaCl are added to 140.g of water?
mass of solution = mass of solute + mass of solvent
35 g
x 100
% Solution by Mass =
35 g g
% Solution by Mass =
20.%

41. Even More Challenging…
What mass of water must be added to 12.5 g of KClO3 to make a solution that has a concentration by mass of 25.0%?
First determine the total mass of the solution:
12.5 g
0.250 =
x = 50.0g x
Then determine the amount of water needed to make a solution with a mass of 50.0g:
50.0g = 12.5g + x
x = 37.5 g

42. Percent Solution by Volume (commonly used for solutions of 2 liquids)
volume of solute
x 100
% Solution by Volume =
volume of solution
What is the percent by volume of a solution of isopropyl alcohol in water if it has a total volume of 120.mL and the volume of pure isopropyl alcohol is 36mL?
30.%

43. Parts Per Million (ppm)
Often used to describe very dilute concentrations of particles that are potentially hazardous to one’s health
What is the concentration in ppm of lead in a sample of drinking water that has a mass of 2.5kg and the mass of lead is g?
20. ppm

44. Part Per Million Example Problem
What is the mass of mercury in a solution that has a mass of kg and a concentration of 300.ppm Hg? x
300.ppm = x
3600.g
First divide both sides by , then solve
X = 1.08 g

45. Colligative Properties
How do the physical properties of water change when a non-volatile solute is added?

46. Boiling Point Elevation and Freezing Point Depression
When a non-volatile solute is added to water, the boiling point increases.
…, the freezing point decreases.
new b.p.
normal
new f.p.

47. Why do we add salt to the roads and sidewalks with a winter storm?
The added salt lowers the freezing point of water, so it helps melt the snow and/or ice.

48. The amount of temperature change is influenced by concentration.
A more concentrated solution would have more of an effect than a less concentrated one.
More concentrated  higher boiling point
More concentrated  lower freezing point
Which solution would have the higher boiling point?
A: 2 M NaCl (aq)
B: 3 M NaCl (aq)

49. Actual temperature for new bp and new fp can be calculated based on molality
For bp: change in bp = molality x 0.51°C/m
For fp: change in fp = molality x 1.86°C/m
What is the boiling point of a 2 m solution?
What is the freezing point of a 2 m solution?

50. Electrolyte vs. Non-electrolyte
Ionic substances, acids, and bases are electrolytes because they break apart into ions when dissolved.
Covalent substances are non-electrolytes because they do not break apart in water.
Helpful Hint: Ionic compounds have a metal or a polyatomic ion, and covalent compounds have all nonmetals.

51. Given the same concentration, the electrolyte will have a greater effect than the non-electrolyte.
Which solution has a lower freezing point?
A: 1 M NaCl (aq) or B: 1 M C12H22O11 (aq)

52. Different ionic compounds may dissociate into a different number of ions:
One mole of NaCl when put in water breaks apart into 1 mole of Na+ and 1 mole of Cl-
One mole of CaCl2 when put in water breaks apart into 1 mole of Ca+2 and 2 moles of Cl-
Which solution has a higher boiling point?
A: 1.5 M NaCl (aq)
B: 1.5 M CaCl2 (aq)

53. Be careful for tricky questions:
Which solution has the lowest boiling point?
A: 1 M NaCl or B: 2 M NaCl
First, ask does boiling point inc or dec?
Then, will the correct answer be the solution that is more or less concentrated?
1 M NaCl

54. Be careful for tricky questions:
Which solution has the highest melting point?
A: 1 M NaCl B: 2 M NaCl
C: 1 M C12H22O11 D: 2 M C12H22O11
First, ask does fp/mp inc or dec?
Then, will the correct answer be the solution that is more or less concentrated?
And, will the correct answer be the electrolyte or the non-electrolyte?