Acids, Bases, and pH2.pdfjejejejjejejeeeue

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1. Acids, Bases, and pH

2. I. What are acids?
■Substances that donate hydrogen ions, H
+
, to
form hydronium ions, H
3
O
+
, when dissolved
in water

3. Formation of Hydronium Ions
1+
hydronium ion
H
3
O
+

+
hydrogen ion
H
+


water
H
2
O
1+
(a proton)

1+

4. A. Characteristics of acids
1. Acids turn blue litmus paper red
Litmus paper is an indicator

2. Acids taste sour

3. Can burn skin

5. Common Acids
Sulfuric AcidH
2
SO
4


Nitric AcidHNO
3


Phosphoric AcidH
3
PO
4


Hydrochloric AcidHCl

Acetic Acid CH
3
COOH

Carbonic Acid H
2
CO
3

Battery acid
Used to make fertilizers
and explosives
Food flavoring
Stomach acid
Vinegar
Carbonated water

6. B. Strong vs. Weak acids
1. Strong acids – ionize (break in to
cations and anions) almost completely,
and conduct electricity well
a. Nitric acid (HNO
3
)
b. Hydrochloric acid (HCl)
c. Sulfuric acid (H
2
SO
4
)
d. Perchloric acid

7. B. Strong vs. Weak acids
2. Weak acids – do not completely ionize
a. Acetic acid (vinegar)
b. Citric acid
c. ALL others

8. II. What are bases?
- Substances that form hydroxide ions (OH
-
)
ions when in water, or accept H
+
ions

10. A. Characteristics of Bases
1. Taste bitter
2. Slippery
3. Bases turn red
litmus paper blue
4. Can burn skin

11. B. Strong vs. Weak bases
1. Strong bases - ionize (break into
cations and anions) almost completely,
and conduct electricity well
a. KOH – potassium hydroxide
b. NaOH – sodium hydroxide
2. Weak bases - do not completely ionize
a. Ammonia (NH
3
)

12. Review
■Acid: A solution that has an excess of H
+

ions. It comes from the Latin word acidus
that means "sharp" or "sour".

■Base: A solution that has an excess of OH
-

ions. Another word for base is alkali.

■Aqueous: A solution that is mainly water.
Think about the word aquarium. AQUA
means water.

13. III. Why is a substance neutral?
■A substance is neutral when:
1. It does not ionize at all, therefore no
H
+
or OH
-
ions
2. It has equal concentrations
(amounts) of H
+
and OH
-
ions

14. IV. How acidic or basic is it?
A. pH – measures the concentration of H
3
O
+
ions

Crowded
Not Crowded

More crowded = More concentrated
Critical to certain processes and functions
- example: enzymes, blood

B. pH indicates H
3
O
+
and OH
-
concentrations

15. Concentration vs. Strength
■Concentration is not the same as strength
■Concentration deals with the amount of
hydronium ions in the solution, compared to
the amount of water in the solution.

More acid or base and less water
= more concentrated
More ions and less molecules
= stronger

17. III. How acidic or basic is it?
C. pH scale 0-14
Indicates concentration of hydronium ions
0-6 = acid closer to 0 is more acidic

8-14 = base closer to 14 is more basic

7 = neutral H
3
O
+
concentration = OH
-

concentrations

19. III. How acidic or basic is it?
D. Each pH unit = a power of ten
- Example: pH 3 is 100 times more
acidic than pH 5

20. Review
■Strong Acid: An acid that has a very low pH (0-4).

■Strong Base: A base that has a very high pH (10-14).

■Weak Acid: An acid that only partially ionizes in an
aqueous solution. That means not every molecule
breaks apart. They usually have a pH close to 7 (3-6).

■Weak Base: A base that only partially ionizes in an
aqueous solution. That means not every molecule
breaks apart. They usually have a pH close to 7 (8-10).

■Neutral: A solution that has a pH of 7. It is neither
acidic nor basic.