copyright © 2005, n. ahbel understanding ph sources: 1. anthony carpi, acids, bases and ph,...
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Copyright
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2005, N. Ahbel
Understanding pHSources:
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
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2005, N. Ahbel
H2OWater Molecule
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H2O H2O
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H2O H2OHO- Hydroxide
H3O+
Hydronium
Proton Exchange
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HO- Hydroxide
H3O+
Hydronium
H2O H2OProton Exchange
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Base High concentration of OH-
Low concentration of H3O+
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2005, N. Ahbel
Acid High concentration of H3O+
Low concentration of OH-
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2005, N. Ahbel
[H3O+]
Concentration in moles/liter
pH[OH-]
Concentration in moles/liter
Example
1 X 100 0 1 X 10-14 Battery acid, Strong HCl (4%)
1 X 10-1 1 1 X 10-13 Stomach acid
1 X 10-2 2 1 X 10-12 Lemon juice
1 X 10-3 3 1 X 10-11 Orange juice, Vinegar, Gastric juices
1 X 10-4 4 1 X 10-10 Acid rain, Tomato juice, Soda
1 X 10-5 5 1 X 10-9 Rainwater (unpolluted), Black coffee
1 X 10-6 6 1 X 10-8 Milk, Urine, Saliva
1 X 10-7 7 1 X 10-7 Pure water
1 X 10-8 8 1 X 10-6 Egg whites
1 X 10-9 9 1 X 10-5 Baking Soda
1 X 10-10 10 1 X 10-4 Tums® (antacid)
1 X 10-11 11 1 X 10-3 Ammonia
1 X 10-12 12 1 X 10-2 Mineral Lime
1 X 10-13 13 1 X 10-1 Bleach, Oven cleaner
1 X 10-14 14 1 X 100 Drano®, NaOH (4%)
Neutral
Acid
Base
Copyright
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2005, N. Ahbel
[H3O+]
Concentration in moles/liter
pH[OH-]
Concentration in moles/liter
Example
1 X 100 0 1 X 10-14 Battery acid, Strong HCl (4%)
1 X 10-1 1 1 X 10-13 Stomach acid
1 X 10-2 2 1 X 10-12 Lemon juice
1 X 10-3 3 1 X 10-11 Orange juice, Vinegar, Gastric juices
1 X 10-4 4 1 X 10-10 Acid rain, Tomato juice, Soda
1 X 10-5 5 1 X 10-9 Rainwater (unpolluted), Black coffee
1 X 10-6 6 1 X 10-8 Milk, Urine, Saliva
1 X 10-7 7 1 X 10-7 Pure water
1 X 10-8 8 1 X 10-6 Egg whites
1 X 10-9 9 1 X 10-5 Baking Soda
1 X 10-10 10 1 X 10-4 Tums® (antacid)
1 X 10-11 11 1 X 10-3 Ammonia
1 X 10-12 12 1 X 10-2 Mineral Lime
1 X 10-13 13 1 X 10-1 Bleach, Oven cleaner
1 X 10-14 14 1 X 100 Drano®, NaOH (4%)
What is pH?pH isthe oppositeof the logof the concentrationof Hydronium ions measured in moles per liter
or
pH = - log (concentration H3O+ )
- log (1 x 10-7 ) = 7
- log (1 x 10-11 ) = 11
- log (1 x 10-3 ) = 3
Examples
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2005, N. Ahbel
[H3O+]
Concentration in moles/liter
pH[OH-]
Concentration in moles/liter
Example
1 X 100 0 1 X 10-14 Battery acid, Strong HCl (4%)
1 X 10-1 1 1 X 10-13 Stomach acid
1 X 10-2 2 1 X 10-12 Lemon juice
1 X 10-3 3 1 X 10-11 Orange juice, Vinegar, Gastric juices
1 X 10-4 4 1 X 10-10 Acid rain, Tomato juice, Soda
1 X 10-5 5 1 X 10-9 Rainwater (unpolluted), Black coffee
1 X 10-6 6 1 X 10-8 Milk, Urine, Saliva
1 X 10-7 7 1 X 10-7 Pure water
1 X 10-8 8 1 X 10-6 Egg whites
1 X 10-9 9 1 X 10-5 Baking Soda
1 X 10-10 10 1 X 10-4 Tums® (antacid)
1 X 10-11 11 1 X 10-3 Ammonia
1 X 10-12 12 1 X 10-2 Mineral Lime
1 X 10-13 13 1 X 10-1 Bleach, Oven cleaner
1 X 10-14 14 1 X 100 Drano®, NaOH (4%)
How much more acidic is orange juice than coffee?
The answer is the ratio of the concentrations of H3O+.
Coffee
Orange juice
-3-3 + 5 2
-5
Concentration of OJ 1 x 10 = = 10 = 10 = 100
Concentration of Coffee 1 x 10
OJ is 100 times as acidic as coffee. This also implies that coffee is 100 times as basic as OJ.
Copyright
©
2005, N. Ahbel
Understanding pHSources:
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