1. Acids/Bases
Svante Arrhenius, a Swedish chemist, proposed the following definition:
Acids form hydronium ions in aqueous solutions, while bases form hydroxide ions.
Acids give off H+
Bases give off OH-

2. Properties of acids Give foods a tart or sour taste Electrolytes
React with hydroxide ions to form water and a salt
HCl + NaOH --> NaCl + H2O

3. Properties of bases React with acids to form water and salt
Have a bitter taste
Have a slippery feel
Electrolytes
Milk of Magnesia (Magnesium Hydroxide) is a base used to treat excess stomach acid problems.

5. Hydrogen Ions from Water This is the basis to start understanding pH
Water is considered neutral
Collision between water molecules can cause a hydrogen ion to transfer from one molecule to another.
H2O H2O H3O OH-
hydronium ion hydroxide ion

6. Self-Ionization of Water
Water self ionizes to the concentration of 1.0 x 10-7 mol/L.
When the concentration of each ion equals 1.0 x 10-7 mol/L
the solution is said to be neutral
Therefore, since water is considered neutral the
concentrations of the ions can be calculated through the
Ion product constant.

8. The Ion-Product Constant Kw
Notation
[H+] - concentration of hydrogen ions
Or hydronium ions
[OH-] - concentration of hydroxide ions
When [H+] and [OH-] are multiplied we get the ion-product constant.
Kw = [H+] x [OH-] = 1.0 x (mol/L)2 or M2
This is an inverse relationship.
One goes up, the other goes down.

9. The Ion-Product Constant Kw example problem
If [H+] = 1.0 x 10-5 mol/L, is the solution acidic, basic, or neutral? What is the [OH-] of this solution?
Answer
Acidic - the [H+] is greater than 1.0 x 10-7 mol/L
1.0 x 10-5 mol/L x [OH-] = 1.0 x M2
[OH-] = 1.0 x 10-9 mol/L

10. The Ion-Product Constant Kw example problem
If [OH-] = 2.8 x 10-8 mol/L, is the solution acidic, basic, or neutral? What is the [H+] of this solution?
Answer
acidic - the [OH-] is less than 1.0 x 10-7 mol/L
[H+] x 2.8 x 10-8 mol/L = 1.0 x M2
[H+] = 3.5 x 10-7 mol/L