1. So l ut i ons

2. Solute Solvent A solute is the dissolved substance in a solution.
Salt in salt water
Sugar in soda drinks
Carbon dioxide in soda drinks
Solvent
A solvent is the dissolving medium in a solution.
Water in salt water
Water in soda

3. “Like Dissolves Like”
Nonpolar solutes dissolve best in nonpolar solvents
Fats
Benzene
Steroids
Hexane
Waxes
Toluene
Polar and ionic solutes dissolve best in polar solvents
Inorganic Salts
Water
Sugars
Small alcohols
Acetic acid

4. Solubility Trends
The solubility of MOST solids increases with temperature.
The rate at which solids dissolve increases with increasing surface area of the solid.
The solubility of gases decreases with increases in temperature.
The solubility of gases increases with the pressure above the solution.

5. Therefore… Solids tend to dissolve best when: Heated Stirred
Ground into small particles
Gases tend to dissolve best when:
The solution is cold
Pressure is high

6. Solubility Chart

7. Saturation of Solutions
A solution that contains the maximum amount of solute that may be dissolved under existing conditions is saturated.
A solution that contains less solute than a saturated solution under existing conditions is unsaturated.
A solution that contains more dissolved solute than a saturated solution under the same conditions is supersaturated.

8. Definition of Electrolytes and Nonelectrolytes
An electrolyte is:
A substance whose aqueous solution conducts an electric current.
A nonelectrolyte is:
A substance whose aqueous solution does not conduct an electric current.

9. Electrolytes vs. Nonelectrolytes
The ammeter measures the flow of electrons (current)
through the circuit.
If the ammeter measures a current, and the bulb
glows, then the solution conducts.
If the ammeter fails to measure a current, and the
bulb does not glow, the solution is non-conducting.

10. Try to classify the following substances as electrolytes or nonelectrolytes…
Pure water
Tap water
Sugar solution
Sodium chloride solution
Hydrochloric acid solution
Lactic acid solution
Ethyl alcohol solution
Pure sodium chloride

11. Answers to Electrolytes
NONELECTROLYTES:
Tap water (weak)
NaCl solution
HCl solution
Lactate solution (weak)
Pure water
Sugar solution
Ethanol solution
Pure NaCl

12. Ionic Compounds “Dissociate”
NaCl(s) 
Na+(aq) + Cl-(aq)
AgNO3(s) 
Ag+(aq) + NO3-(aq)
MgCl2(s) 
Mg2+(aq) + 2 Cl-(aq)
Na2SO4(s) 
2 Na+(aq) + SO42-(aq)
AlCl3(s) 
Al3+(aq) + 3 Cl-(aq)

13. Ions tend to stay in solution where they can conduct a current rather than re-forming a solid.
The reason for this is the polar nature of
the water molecule…
Positive ions associate with the negative
end of the water dipole (oxygen).
Negative ions associate with the positive
end of the water dipole (hydrogen).

14. Some covalent compounds IONIZE in solution
Covalent acids form ions in solution, with the
help of the water molecules.
For instance, hydrogen chloride molecules,
which are polar, give up their hydrogens to
water, forming chloride ions (Cl-) and
hydronium ions (H3O+).

15. Strong acids such as HCl are completely ionized in solution.
Other examples of strong acids include:
Sulfuric acid, H2SO4
Nitric acid, HNO3
Hydriodic acid, HI
Perchloric acid, HClO4

16. Weak acids such as lactic acid usually ionize less than 5% of the time.
Many of these weaker acids
are “organic” acids that contain a “carboxyl” group.
The carboxyl group does not easily give up its
hydrogen.

17. Other organic acids and their sources include:
Because of the carboxyl group, organic acids are sometimes called “carboxylic acids”.
Other organic acids and their sources include:
Citric acid – citrus fruit
Malic acid – apples
Butyric acid – rancid butter
Amino acids – protein
Nucleic acids – DNA and RNA
Ascorbic acid – Vitamin C
This is an enormous group of compounds;
these are only a few examples.