1. Copyright © 2005, N. Ahbel Understanding pH Sources: 1. Anthony Carpi, Acids, Bases and pH, http://web.jjay.cuny.edu/~acarpi/NSC/7-ph.htm, 1998-1999 2. Paul Decelles, The pH Scale, http://staff.jccc.net/pdecell/chemistry/phscale.html, 6/20/2002 http://web.jjay.cuny.edu/~acarpi/NSC/7-ph.htm http://staff.jccc.net/pdecell/chemistry/phscale.html

2. Copyright © 2005, N. Ahbel H2OH2O Water Molecule

3. Copyright © 2005, N. Ahbel H2OH2OH2OH2O

4. H2OH2OH2OH2OHO - Hydroxide H 3 O + Hydronium Proton Exchange

5. Copyright © 2005, N. Ahbel HO - Hydroxide H 3 O + Hydronium H2OH2OH2OH2O Proton Exchange

6. Copyright © 2005, N. Ahbel Base High concentration of OH - Low concentration of H 3 O +

7. Copyright © 2005, N. Ahbel Acid High concentration of H 3 O + Low concentration of OH -

8. Copyright © 2005, N. Ahbel [H 3 O + ] Concentration in moles/liter pH [OH - ] Concentration in moles/liter Example 1 X 10 0 01 X 10 -14 Battery acid, Strong HCl (4%) 1 X 10 -1 11 X 10 -13 Stomach acid 1 X 10 -2 21 X 10 -12 Lemon juice 1 X 10 -3 31 X 10 -11 Orange juice, Vinegar, Gastric juices 1 X 10 -4 41 X 10 -10 Acid rain, Tomato juice, Soda 1 X 10 -5 51 X 10 -9 Rainwater (unpolluted), Black coffee 1 X 10 -6 61 X 10 -8 Milk, Urine, Saliva 1 X 10 -7 7 Pure water 1 X 10 -8 81 X 10 -6 Egg whites 1 X 10 -9 91 X 10 -5 Baking Soda 1 X 10 -10 101 X 10 -4 Tums® (antacid) 1 X 10 -11 111 X 10 -3 Ammonia 1 X 10 -12 121 X 10 -2 Mineral Lime 1 X 10 -13 131 X 10 -1 Bleach, Oven cleaner 1 X 10 -14 141 X 10 0 Drano®, NaOH (4%) Neutral Acid Base

9. Copyright © 2005, N. Ahbel [H 3 O + ] Concentration in moles/liter pH [OH - ] Concentration in moles/liter Example 1 X 10 0 01 X 10 -14 Battery acid, Strong HCl (4%) 1 X 10 -1 11 X 10 -13 Stomach acid 1 X 10 -2 21 X 10 -12 Lemon juice 1 X 10 -3 31 X 10 -11 Orange juice, Vinegar, Gastric juices 1 X 10 -4 41 X 10 -10 Acid rain, Tomato juice, Soda 1 X 10 -5 51 X 10 -9 Rainwater (unpolluted), Black coffee 1 X 10 -6 61 X 10 -8 Milk, Urine, Saliva 1 X 10 -7 7 Pure water 1 X 10 -8 81 X 10 -6 Egg whites 1 X 10 -9 91 X 10 -5 Baking Soda 1 X 10 -10 101 X 10 -4 Tums® (antacid) 1 X 10 -11 111 X 10 -3 Ammonia 1 X 10 -12 121 X 10 -2 Mineral Lime 1 X 10 -13 131 X 10 -1 Bleach, Oven cleaner 1 X 10 -14 141 X 10 0 Drano®, NaOH (4%) What is pH? pH is the opposite of the log of the concentration of Hydronium ions measured in moles per liter or pH = - log (concentration H 3 O + ) - log (1 x 10 -7 ) = 7 - log (1 x 10 -11 ) = 11 - log (1 x 10 -3 ) = 3 Examples

10. Copyright © 2005, N. Ahbel [H 3 O + ] Concentration in moles/liter pH [OH - ] Concentration in moles/liter Example 1 X 10 0 01 X 10 -14 Battery acid, Strong HCl (4%) 1 X 10 -1 11 X 10 -13 Stomach acid 1 X 10 -2 21 X 10 -12 Lemon juice 1 X 10 -3 31 X 10 -11 Orange juice, Vinegar, Gastric juices 1 X 10 -4 41 X 10 -10 Acid rain, Tomato juice, Soda 1 X 10 -5 51 X 10 -9 Rainwater (unpolluted), Black coffee 1 X 10 -6 61 X 10 -8 Milk, Urine, Saliva 1 X 10 -7 7 Pure water 1 X 10 -8 81 X 10 -6 Egg whites 1 X 10 -9 91 X 10 -5 Baking Soda 1 X 10 -10 101 X 10 -4 Tums® (antacid) 1 X 10 -11 111 X 10 -3 Ammonia 1 X 10 -12 121 X 10 -2 Mineral Lime 1 X 10 -13 131 X 10 -1 Bleach, Oven cleaner 1 X 10 -14 141 X 10 0 Drano®, NaOH (4%) How much more acidic is orange juice than coffee? The answer is the ratio of the concentrations of H 3 O +. Coffee Orange juice OJ is 100 times as acidic as coffee. This also implies that coffee is 100 times as basic as OJ.

11. Copyright © 2005, N. Ahbel Understanding pH Sources: 1. Anthony Carpi, Acids, Bases and pH, http://web.jjay.cuny.edu/~acarpi/NSC/7-ph.htm, 1998-1999 2. Paul Decelles, The pH Scale, http://staff.jccc.net/pdecell/chemistry/phscale.html, 6/20/2002 http://web.jjay.cuny.edu/~acarpi/NSC/7-ph.htm http://staff.jccc.net/pdecell/chemistry/phscale.html