1. UNIQUE PROPERTIES OF WATER: Water can break apart to form hydrogen ions (H+) and hydroxide ions (OH-). Water can break apart to form hydrogen ions (H+) and hydroxide ions (OH-). **These two ions are the most reactive ions in nature. ** ACIDS and BASES 

2. Acids and Bases The pH scale is used to determine the strength of acid or base by measuring the concentration of H+ ions. The pH scale is used to determine the strength of acid or base by measuring the concentration of H+ ions. An acid and base can neutralize each other to form a salt and water. An acid and base can neutralize each other to form a salt and water.

3. pH Scale 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 A. Acid B. Neutral C. Base Stronger acid Stronger base

4. In a neutral substance like pure water, the concentration of hydrogen and hydroxide ions equal each other. In a neutral substance like pure water, the concentration of hydrogen and hydroxide ions equal each other. H+ = OH - An acid is any compound that produces H+ ions when it dissolves in water. Examples: HCl and H 2 SO 4. An acid is any compound that produces H+ ions when it dissolves in water. Examples: HCl and H 2 SO 4. H+ > OH - A base is any compound that produces OH- ions when it dissolves in water. Examples: NaOH and KOH. A base is any compound that produces OH- ions when it dissolves in water. Examples: NaOH and KOH. H+ < OH -