1. Components of a Solution
Solute: substance being dissolved
Ex: Salt, Sugar
Solvent: substance doing the dissolving
Ex: Water, Hexane

2. Solubility: How much solute can dissolve under certain conditions of
temp. and pressure.

3. Miscible:
2 liquids that dissolve
(ex: alcohol and water)
Immiscible:
2 liquids that do not dissolve (ex: oil and water)

4. Factors Affecting Solubility
Surface Area
More solute/solvent contact
means faster dissolving
Crush substance into fine
powder
Use mortar and pestle

5. Stirring or Agitation:
More solute/solvent
contact (solids/liquids)
However, stirring disturbs
dissolved gases and they
come out of solution.

6. Temperature of Solvent
Higher temperatures will allow more
solid solutes to dissolve

7. Gases dissolve better when solvent temperature is colder.
Ex: CO2 gas in hot soda (flat) vs. cold soda (fizzy)

8. Pressure
Effects gas solubility only
Why?
Increasing pressure on
a gas above a liquid
causes more gas
molecules to be
“pushed” into solution.
Ex: CO2(aq) in soda

9. Nature of Solute and Solvent
Polar solutes dissolve in polar solvents
Nonpolar solutes dissolve in nonpolar solvents
Most ionics (but not all) dissolve in polar solvents (molecule-ion attractions)

10. Amount of Solute already Dissolved
As particles dissolve in solution fewer
solvent molecules are available to dissolve
new solute.

11. Electrolytes
Conduct electricity when dissolved in water

12. Why do they Conduct? Create mobile ions in solution.
The more concentrated the solution the more it conducts
Includes:
Soluble Ionic Compounds (ex: NaCl)
Acids (ex: HCl)
Bases (ex: NaOH)

13. Who Will Conduct?
Which of the following compounds will conduct in solution? (ionic salt, acid, base?)
See Ref Tables for common acids/bases
C6H12O6
LiBr
KOH
CH4
H2SO4
NO2

14. Using Reference Table G
Shows solubility in grams of solute per 100 grams of water at different temps

15. Saturated Solutions:
hold max solute
possible at that temp.
Table G:
Solubility curve lines
show saturation levels
at different temps

16. Saturated Solutions are at EQUILIBRIUM.
Rate of dissolving = Rate of crystallization

17. Go to 50 °C and up to NaNO3 and over.
Ex: How many grams of NaNO3 are needed to create a sat. solution in 100g of water at 50 °C?
Go to 50 °C and up to NaNO3 and over.
Answer: 116 grams

18. Look at The Water!! Table G is for 100 grams of water.
Amount of water in your problem may be different and you need to adjust your answer.

19. How many grams of NaNO3 are needed to
create a sat. solution in 300g of water at 50 °C?
Answer: 116 grams x 3
(three times as much water!)
Or you can use a proportion:
116 grams = x grams
100 g H g H20

20. Unsaturated Solutions
could still hold more
solute at that temp.
Would fall “below the line”
on Table G
Ex: 40 g of NaNO3 in 100g water at 50°

21. Supersaturated Solutions
hold more solute than they
should at that temp.
Would fall “above the line”
on Table G
Ex: 140 g of NaNO3 in 100g water at 50°

22. How do Supersaturated Solutions Form?
Create a saturated solution at a high temp. and slowly let solution cool.
Certain solutes can stay in solution.
Ex: sodium acetate
Supersaturated solutions are unstable.
Add just one more “seed crystal”, all excess solute will precipitate leaving a saturated solution behind
Supersaturated Sodium Acetate solution after seed crystal added

23. Describe These Solutions
Saturated, Unsaturated or Supersaturated?

24. 100 g NH4Cl at 70° in
100 g water
Falls above the line (Supersaturated)

25. 10g SO2 at 10° in 100g
water
Falls below the line (Unsaturated)

26. 40g NaCl at 90° in 100g
water
Falls on the line (Saturated)

27. Concentrated Solutions:
have a lot of solute
dissolved in the solvent
Ex: Saturated solution of KI
at 10°
135 grams in 100 g water = pretty concentrated

28. Dilute Solutions: only
have a little solute
dissolved.
Ex: Sat. solution of SO2 at 50°
4 grams in 100 g water = relatively dilute

29. If Temp. Changes
How much will precipitate out of solution if a saturated NaNO3 solution at 60° is cooled to 20° ?

30. Reference Table F
Describes which ionic compounds are soluble or insoluble in water.
Certain combinations of ions hold together so strongly that water cannot dissolve them into solution (insoluble)

31. Is this soluble or not? CaCO3
Carbonate (CO3-2) is insoluble and Ca+2 as a partner is not an exception

32. Is this soluble or not? NaNO3
Nitrate (NO3-1) is always soluble, there are not exceptions

33. Is this soluble or not? Li3PO4
Phosphate (PO4-3) is insoluble, however, Li+1 is a Group 1 ion so it is an exception and the compound is soluble.

34. Soluble or Not?
Look out for exceptions!
CaSO4
MgSO4
PbCrO4
Li2S
NH4OH

35. Precipitates
Precipitates are insoluble ionic compounds formed in double replacement reactions.
Determine which product is the insoluble precipitate by using Table F.

36. When a precipitate forms, you create a heterogeneous mixture.
You can separate a precipitate by filtration.
The solid will stay on the paper.

37. Get Ready! Today’s Agenda Have out: Prelab Sheet
Review Prelab Sheet in pairs and as class.
Review procedure basics as well as safety issues
Divide into groups and get all necessary materials quickly and safely
Perform Lab Procedure and Collect Data
Clean up
Have out:
Prelab Sheet
Solubility of a Salt Lab
Pencil
Calculator

38. Lesson Frame What is the solubility of KNO3 at different temperatures?
How can we construct and interpret a solubility curve?
Crystallization of KNO3
What to look out for:

39. Lab Groups #1: #2: #3: #4: #5: 1st person gets goggles
2nd person gets aprons
3rd person measures KNO3 at scale
4th person gets hot water bath going
5th person reads procedure out loud to group