CHAPTER 23 Solutions

1
CHAPTER 23Solutions

• Section 23.3
• Solubility

2
Solutions include

• Solvent does the dissolving
• Solute gets dissolved.

3
What happens when a salt
(solute) dissolves in a solvent?
4

• A single crystal of salt is a cube.

• Millions of Na and Cl atoms make up the
  cube.

5
The bond between Na and Cl is ionic.

• Chlorine atom has negative charge (Cl-)
• Sodium atom has positive charge (Na).
• Opposite charges attract.

6
Water molecules bond with each other.

• Water has a partially charged negative (?-)
  end and

partially charged positive
(?) ends.
Oxygen
(?-)
7
HYDROGEN BONDSWater molecules weakly connect to
each other by matching positive end to the
negative end of another molecule.
8
(No Transcript)
9
Water molecules hydrate Na and Cl.

• The partially charged ends of water molecules
  attract Na and Cl in the crystal and pull them
  off as ions (Na and Cl-)

10
(No Transcript)
11
When Na and Cl- ions are completely surrounded
by water, the ions are hydrated.
12
Show Hydrated ions by writing aq next to the
ion. Aq means aqueous or water solution.
Na(aq) Cl(aq)-
13
Hydration continues, layer by layer, until the
entire crystal is dissolved, or until the
saturation point is reached.
14

• SATURATION POINT
• EQUILIBRIUM
• As many solute
• molecules are
• dissolving as
• are coming back
• out of solution.

15
SOLUBILITY

• Amount of solute that will dissolve in a specific
  amount of solvent under certain conditions.

16

• Solubility depends on

• Chemical nature of solvent.
• Temperature of the solution.
• Volume of solvent.

17
Chemical nature

• Some solutes are more soluble in a solvent than
  others.
• INSOLUBLE - If a substance does not dissolve in a
  solvent.
• Chalk in H2O

18
Temperature

• Solubility of a salt in a liquid increases with
  an increasing temperature.
• Solubility of a gas in a liquid increases with
  decreasing temperature.

19
Volume

• More solvent volume means more solute can
  dissolve.

20
Solubility values

• Mass of solute that can dissolve in a mass or
  volume of solvent at a certain temperature.

21
Solubility (g salt/100 mL)
Temperature (degrees Celsius)
22
Solubility of Gases

• Depends on pressure, as well as temperature.
• Solubility of a gas in a liquid increases ( )
  with increasing ( ) pressure.

23
How much is dissolved?

• Saturated no more solute will dissolve full.
• Unsaturated more solute can be dissolved not
  full.
• Supersaturated more solute is dissolved than is
  normally possible unstable.

24
To supersaturate a solution

• Add solute until solution is saturated.
• Then heat and add more solute.
• Cool down to normal temperature.