1. Acids, Bases, and pH A water molecule can react to form ions. Water   Hydrogen ion + Hydroxide ion

2. The pH scale Indicates the concentration of hydrogen ions in solution. Ranges from 0-14 7 = neutral or H = OH Pure water has a pH of 7. Each step on scale represents a factor of 10. Solution with pH of 4 has 10 times as many H ions as a solution with pH of 5.

3. The pH scale AcidsBases Any compound that forms H + ions in solution. pH will be lower than 7 Hydrochloric acid produced by the stomach to digest food is a strong acid with pH around 1.5 Any compound that forms OH - ions in solution. pH will be higher than 7 Bleach has a pH of 12.5

4. Buffers Are weak acids or bases that can react with strong acids or bases to prevent sharp, sudden changes in pH. Our body needs buffers to control pH in order to maintain homeostasis. Our body cells generally like to be kept in a pH between 6.5 and 7.5.

5. Check Rainwater (pH 5.5), Tomato Juice (pH 4.0), Gastric juice (pH 2.0). Which has the highest concentration of OH - ? When pH in the stomach increases from 3 to 5, how does the hydrogen ion concentration change?