1. Ch. 13/14: Solutions
Dissolution Factors

2. Dissolution process of dissolving a solute into a solvent
can speed up the process

3. Surface Area Surface area-
how much of the solute is exposed to the solvent
dissolution occurs at the surface of the solute
the more finely divided the solute is, the greater the surface area and the more quickly it dissolves

4. Agitation stirring or shaking a solution
increases the rate of dissolution because the solute particles are more evenly dispersed in the solution
brings fresh solute in contact with the solvent molecules

5. Heating
As the temperature increases, the rate of dissolution increases
Why?
solvent molecules move faster because they have higher KE
This helps to separate solute molecules from each other and evenly disperse them

6. Heating

7. Solubility
For every combination of solute and solvent at a certain temperature, there is a certain amount of solute that can dissolve
depends on the characteristics of solute, solvent and temperature

8. Solubility
As solute particles dissolve, some will hit the surface of solute crystal and reattach
Eventually, the rate of dissolution and recrystallation will be equal
What does this create?
Solution Equilibrium
state in which opposing processes of dissolution and recrystallation occur at equal rates

9. Solution Equilbrium

10. Saturated Solutions Saturated Solution Unsaturated solution
solution that contains the maximum amount of dissolved solute
if more solute is added, it will fall to the bottom and not dissolve
Unsaturated solution
solution that contains less than the maximum amount of solute

11. Supersaturated Solutions
solution that contains more than the maximum amount of solute
can be created by heating up a solution and dissolving as much solute as possible
must allow it to cool undisturbed
will recrystallize quickly if seed crystal is added

12. Supersaturated Solution

13. Use of Recrystallization
Only pure substances can crystallize
Can be used as a separation technique.
Crystals of KNO3 separated from an aqueous solution of KNO3 and CuSO4 (an impurity).
The pale blue color of the solution is produced by Cu2+ ions, which remains in solution

14. Solubility Values
amount of substance required to make a saturated solution
usually given in grams per 100. mL of water
Substance
0°C
20°C
AgNO3
122
216
Ba(OH)2
1.67
3.89
Ce2(SO4)3
20.8
10.1
KCl
28.0
34.2
Li2CO3
1.54
1.33
CO2(g)
0.335
0.169