2. C11-4-10 SOLUBILITY AND PRECIPITATION
OUTCOME QUESTION(S):
C SOLUBILITY AND PRECIPITATION
Explain which factors can affect solubility of solids, liquids, and gases
Differentiate among saturated, unsaturated, and supersaturated solutions using a graph of solubility data and solve problems
Explain solubility and precipitation using balanced ionic and net ionic equations
Use a table of solubility rules to predict the formation of a precipitate
Vocabulary & Concepts 

3. Factors that affect Solubility
Nature of the Solvent and Solute
The general dissolving rule is like dissolves like
Remember that solubility is a relative term
Solute
Solvent
Polar
Non-polar
Ionic √ X

4. 2. Surface area (crushing)
Dissolves faster with increased surface area
Amount dissolved depends on level of attraction
Agitate (stir) the mixture
Added energy of stirring increases dissolving
Dissolving requires energy (endothermic process)

5. Increasing temperature of solids in a solvent increases solubility.
4a. Temperature
Increasing temperature of solids in a solvent increases solubility.
Adding heat provides needed energy to separate the solute and solvent particles H O - + H O - + H O - + H O - + H O - + H O - + H O C + - H O C + - H O C + - H O C + - H O C + -
Attractive Force

6. 4b. Temperature
Increasing temperature of gases in a solvent decreases solubility.
FLAT
The increased temperature gives the dissolved gas particles the energy needed to overcome attractive forces and escape

7. 5. Pressure (only affects gases) Increased pressure on gas solute
increases solubility in a solvent.
Forces gas particles into
contact with the liquid
Gas particles are high energy and only have a weak attraction to solvent particles – this is easily overcome…

8. Data showing the relationship between solubility and temperature.
Solubility Curve
Data showing the relationship between solubility and temperature.
Solubility curves show saturation amounts for a solute dissolving in 100 g of H2O over a range of temperatures
Water has a density of 1 g/ml:
100 g of H2O is 100 mL
Solubility generally increases with temperature – but exceptions exist

9. At 50oC: 100 g H2O is saturated with 90 g of KNO3 dissolved
Solubility creates three types of solutions:
1. Saturated
Maximum amount dissolved at that temperature
At 50oC: 100 g H2O is saturated with 90 g of KNO3 dissolved
2. Unsaturated
Could still dissolve more
at that temperature
3. Supersaturated
Special case - Holding more than
expected at that temperature

10. Supersaturation is achieved using temperature and patience…
100 g of glucose was placed in a beaker of water:
Heat
Bump, shake,
add seed crystal
Stir
Supersaturated solutions are very unstable

11. Use proportions to find missing values
How much can be dissolved in 500 mL?
Solubility is directly proportional to volume
30 g
250 mL
500 mL
Saturated
Saturated
30 g = g
250 mL 60
(500 mL)
(500 mL)
500 mL
Use proportions to find missing values

12. 2.5x the solvent can dissolve 2.5x the solute.
If 25.0 g of solute saturates 40.0 g of solvent, what is the solubility in 100 g of solvent (at the same temperature)?
Use proportions
Make a prediction…
grams of solute1 = grams of solute2
grams of solvent1 grams of solvent2
25.0 g1 = g2
40 g1
62.5
(100 g2)
(100 g2)
100 g2
2.5x the solvent can dissolve 2.5x the solute.

13. grams of solute1 = grams of solute2
If 30.1 g of solute dissolves in mL of water, what is the solubility in 100g of water (at the same temperature)?
Make sure units match…
Water has a density of 1 g/ml:
100 g of H2O is 100 mL
grams of solute1 = grams of solute2
grams of solvent1 grams of solvent2
30.1 g1 = g2
350.0 mL1
8.60
(100 g2)
(100 g2)
100 mL2
About ¼ the solvent can dissolve about ¼ solute.

14. About 2x the solute requires about 2x the solvent.
What volume of water is required to dissolve 240 g of KNO3 at 60°C?
grams of solute1 = grams of solute2
mL of solvent mL of solvent2
113 g1
240 g2
Make a prediction…
212 g2 =
100 g1
? g2
About 2x the solute requires about 2x the solvent.
Create a proportion using the information from the graph for the given temperature =
240 g2
? g2
100 g1
113 g1
113

15. 75 mL of a saturated solution of KNO3 at 70°C is cooled to 40°C
75 mL of a saturated solution of KNO3 at 70°C is cooled to 40°C. What amount will precipitate out?
Use proportions
Lowering temperature lowers solubility =
75.0 mL2
100 mL1
140 g1
105 g2
? g2
At 70oC:
Ask: What does “saturated” look like for this volume of solvent? =
75.0 mL2
100 mL1
65 g1
49.5 g2
? g2
At 40oC:
105 g – 49.5 g = 55.5 g
will precipitate out
140 65 70

16. C11-4-10 SOLUBILITY AND PRECIPITATION
CAN YOU / HAVE YOU?
C SOLUBILITY AND PRECIPITATION
Explain which factors can affect solubility of solids, liquids, and gases
Differentiate among saturated, unsaturated, and supersaturated solutions using a graph of solubility data and solve problems
Explain solubility and precipitation using balanced ionic and net ionic equations
Use a table of solubility rules to predict the formation of a precipitate
Vocabulary & Concepts