Section 16.1 lecture, on factors affecting solubility and rates of dissolution, for honors and prep chemistry

1. 16.1
The interaction between solvent
and solute determines how much a
substance will dissolve.
Solubility = How much solute
dissolves in a certain amount of
solvent
Example- the solubility of sugar is
203g/100mL at 20°C
Insoluble compound = has a
solubility less than 0.1g/100mL.

2. 16.1
Temperature also determines
how much a substance will
dissolve.

3. 16.1
A saturated solution contains
the maximum amount of solute
for a given quantity of solvent at a
given temperature and pressure.
An unsaturated solution
contains less solute than a
saturated solution.

4. 16.1
In a saturated
solution, the rate of
dissolving equals
the rate of
crystallization, so
the total amount of
dissolved solute
remains constant.

5. 16.1
Some liquids combine in all proportions,
while others don’t mix at all.
–Two liquids are miscible if
they dissolve in each other in
all proportions.
–Two liquids are immiscible if they are
insoluble in each other.

6. 16.1
Oil and water are immiscible.

7. 16.1
Vinegar and oil are immiscible.

8. 16.1
Temperature affects the solubility of
anything.
Pressure affects the solubility of a gas.

9. 16.1
Temperature
–The solubility of a solid
increases as the temperature
of the solvent increases.
–The solubility of a gas
decreases as temperature
increases.

10. 16.1
The mineral deposits
around hot springs
result from the
cooling of the hot,
saturated solution of
minerals emerging
from the spring.

11. 16.1

12. 16.1
A supersaturated solution contains
more solute than it can theoretically
hold at a given temperature.
Crystallization of the extra solute can be initiated
if a very small crystal of the solute is added.

13. 16.1
A supersaturated solution is clear before a
seed crystal is added.

14. 16.1
Crystals begin to form in the solution
immediately after the addition of a seed
crystal.

15. 16.1
Excess solute crystallizes rapidly.

16. 16.1

17. 16.1
Pressure
Changes in pressure have little effect
on the solubility of solids and liquids.
Gas solubility increases as the
partial pressure of the gas
above the solution increases.

18. 16.1
Honors only
Henry’s law states that at a given
temperature, the solubility (S) of a gas
in a liquid is directly proportional to the
pressure (P) of the gas above the liquid.

24. The factors that determine how
fast a substance dissolves are
•stirring (agitation)
•Temperature (also affects how much
dissolves)
•the surface area of the dissolving
particles

25. 16.1
A cube of sugar in cold tea dissolves slowly.

26. 16.1
Granulated sugar dissolves in cold water more
quickly than a sugar cube, especially with stirring.

27. 16.1
Granulated sugar dissolves very quickly in hot tea.

28. At higher temperatures molecules
move faster.
Water molecules surround and
remove the solute particles from
the solid more quickly.

29. 16.1
Particle Size and Solution Formation
A spoonful of granulated sugar
dissolves more quickly than a sugar
cube because the smaller particles in
granulated sugar expose a much
greater surface area to the colliding
water molecules.

30. 16.1
Stirring and Solution Formation
Stirring speeds up the dissolving
process because fresh solvent (the
water in tea) is continually brought into
contact with the surface of the solute
(sugar).

31. 16.1 Section Quiz.
1. For a given substance, which of the following
will NOT influence how fast it dissolves?
a. temperature
b. amount of agitation
c. molar mass
d. size of the crystals

32. 16.1 Section Quiz.
3. The solubility of a gas in a solvent is affected
by
a. both temperature and pressure.
b. only pressure.
c. only temperature.
d. both pressure and agitation.