Acids, Bases, and Salts

A.  Acids

1.  An acid is a substance that produces hydrogen ions (H+) in solution

2.  Acid properties:

a.  Acids taste sour (never use the taste test, however!)

b.  Acids are electrolytes

c.  Acids are corrosive (they "eat away" some metals)

d.  Acids turn litmus paper red (litmus is an indicator)

e.  Acids react with metals to produce hydrogen gas

f.  Acids have a pH less than 7

g.  Acids neutralize bases

3.  Some common acids

a.  Sulfuric acid

1)  The most widely used chemical in the world

2)  Most of it is used to make fertilizer

3)  It is a good dehydrating agent

4)  It is used in car batteries

b.  Phosphoric acid

1)  Most is used to make fertilizer

2)  In a very dilute form, it is used in soft drinks

3)  It is added to detergents, but can cause pollution problems as phosphates

c.  Nitric acid

1)  Most is used to make fertilizer

2)  It is most well known for making explosives

d.  Hydrochloric acid

1)  Most is used to clean metals (pickling)

2)  Also called muriatic acid

B.  Bases

1.  A base is a substance that produces hydroxide ions (OH-) in solution

2.  Base properties:

a.  Bases feel slippery

b.  Bases are electrolytes

c.  Bases are corrosive, poisonous, and can cause severe burns

d.  Bases turn litmus blue

e.  Bases have a pH greater than 7

f.  Bases neutralize acids

3.  Some common bases

a.  Ammonia

1)  The most widely used base

2)  Used in household cleaning materials

3)  Used as fertilizer

b.  Calcium hydroxide (caustic lime)

1)  Used  to make mortar and plaster

2)  Used to help neutralize acid soil

c.  Sodium hydroxide (lye)

1)  One of the strongest bases

2)  Used in oven cleaners and drain cleaners

C.  Solutions of Acids and Bases

1.  Hydrogen ions given off by acids combine with water molecules to form hydronium ions

2.  Solutions that have more hydronium ions than hydroxide ions are acidic

3.  If they have more hydroxide ions than hydronium ions, they are basic

D.  Strength of Acids and Bases

1.  Strong acids or bases ionize almost completely in solution

2.  Weak acids or bases only partly ionize

3.  The pH scale

a.  "Power of hydrogen ions"

b.  Diagram:

strongest acid                  neutral                          strongest base

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0    1    2    3    4    5    6    7    8    9    10    11    12    13    14

E.  Acids, Bases, and Salts

1.  Neutralization

a.   A chemical reaction between an acid and a base

b.  Acid + Base  ---->  Salt + Water

2.  Salts are compounds made from the negative ions of an acid that combine with the positive ions of a base

3.  Titration

a.  A method of finding the concentration of a solution using another solution of known concentration

b.  Phenolphthalein is commonly used as the indicator (turns pink in base, but is colorless in acid)