Acid and Bases
LAB 6. ACIDS AND BASES:
PH AND BUFFERS
PURPOSE: To determine the pH of common acids and bases using a pH meter, pH paper, and red cabbage indicator.
To test the effect of adding an acid or base to a buffer solution.
SAFETY CONCERNS:
Always wear safety goggles.
Wash with soap and water if skin contacts acids or bases.
ACIDS:
An Acid is a substance that when dissolved in water will produce hydrogen ions, H+, in the solution. An acid that does not contain carbon is called an inorganic acid. An acid that contains carbon is called an organic acid.
Strong acids are acids that produce lots of hydrogen ions, H1+’s. They almost completely
dissociate (break apart) to form hydrogen cations, H1+, and the companion anions. Once dissolved in water the very strong acid does not exist any more since it has dissociated into its ions. H-Cl H1+ + Cl1-
Dissociation of Hydrochloric acid
Examples of Strong Acids:
Strong Acid
Hydrochloric Acid
Sulfuric Acid
Formula
HCl
Common Source
H2SO4
Battery Acid
Stomach Acid
Weak acids are acids that produce only a few hydrogen ions, H1+’s. Only some of the
molecules in solution dissociate (break apart) into hydrogen cations, H1+, at a time. When they do break apart, the hydrogen cations, H1+, and the companion anions join back together again to reform the acid. This process of the acid breaking apart and then reforming over and over is called equilibrium. Because of the equilibrium there is a mixture of the original acid, the hydrogen ion, H1+, and the anion all in the solution at the same time.
Dissociation of Acetic acid
H-C2H3O2 H1+ + C2H3O21-
Dissociation of
Carbonic acid
CO2 + H2O H2CO3 H1+ + HCO31CH110 Lab 6. Acids and Bases
61
Examples of Weak Acids:
Weak Acid
Acetic Acid
Formula
HC2H3O2
Common Source
Carbonic Acid
H2CO3
In Carbonated Water
Citric Acid
H3C6H5O7
In Lemons & Oranges
Tartaric Acid
H2C4H4O6
In Grapes
PH AND BUFFERS
PURPOSE: To determine the pH of common acids and bases using a pH meter, pH paper, and red cabbage indicator.
To test the effect of adding an acid or base to a buffer solution.
SAFETY CONCERNS:
Always wear safety goggles.
Wash with soap and water if skin contacts acids or bases.
ACIDS:
An Acid is a substance that when dissolved in water will produce hydrogen ions, H+, in the solution. An acid that does not contain carbon is called an inorganic acid. An acid that contains carbon is called an organic acid.
Strong acids are acids that produce lots of hydrogen ions, H1+’s. They almost completely
dissociate (break apart) to form hydrogen cations, H1+, and the companion anions. Once dissolved in water the very strong acid does not exist any more since it has dissociated into its ions. H-Cl H1+ + Cl1-
Dissociation of Hydrochloric acid
Examples of Strong Acids:
Strong Acid
Hydrochloric Acid
Sulfuric Acid
Formula
HCl
Common Source
H2SO4
Battery Acid
Stomach Acid
Weak acids are acids that produce only a few hydrogen ions, H1+’s. Only some of the
molecules in solution dissociate (break apart) into hydrogen cations, H1+, at a time. When they do break apart, the hydrogen cations, H1+, and the companion anions join back together again to reform the acid. This process of the acid breaking apart and then reforming over and over is called equilibrium. Because of the equilibrium there is a mixture of the original acid, the hydrogen ion, H1+, and the anion all in the solution at the same time.
Dissociation of Acetic acid
H-C2H3O2 H1+ + C2H3O21-
Dissociation of
Carbonic acid
CO2 + H2O H2CO3 H1+ + HCO31CH110 Lab 6. Acids and Bases
61
Examples of Weak Acids:
Weak Acid
Acetic Acid
Formula
HC2H3O2
Common Source
Carbonic Acid
H2CO3
In Carbonated Water
Citric Acid
H3C6H5O7
In Lemons & Oranges
Tartaric Acid
H2C4H4O6
In Grapes