Acids and Bases
Acids
O Acids are compounds that add (H+) ions
to water when in a solution.
H+
Cl-
H+
In Water
Cl-
O HCl: a very strong acid. In water it
breaks up (dissociates) and adds H+ to
the water.
Bases
O Bases are compounds that add (OH-) ions to
when in a solution.
water
Na+
H+
Na+
O2-
In water
O2-
H+
O NaOH: a very strong base. In water it breaks up
(dissociates) and adds OH- to the water.
Common Acids
O Many foods are acidic:
Tomatoes
Lemons
Oranges
Limes
Apples
vinegar
O Acids taste
sour
and feel
squeaky when you rub them
between your fingers
Common Bases
O Many cleaners are basic:
Soap
Bleach
ammonia (Windex)
O Bases taste
bitter and feel
slippery when you rub
them between your fingers
Question #1
O Are antacids acids
or bases?
O Why?
Safety
O Acids are corrosive! They can
burn your skin or eyes.
O Bases are caustic! They can
burn your skin or eyes.
O Why do you think the safety
sign for acids and bases is the
same sign?
Other Terms
O Strong acids and bases—
ionize (dissolve)
completely in water,
adding many ions to the
water
O Weak acids and bases—do
not ionize (dissolve)
completely in water,
adding fewer ions to the
water.
The pH Scale
Litmus Paper
O Acids are indicated by
a Red color.
O If Red litmus paper is
dipped in an acid it will
stay Red
O If Blue litmus paper is
dipped in an acid it will
turn Red
Litmus Paper
O Bases are indicated by
a Blue color.
O If Blue litmus paper is
dipped in a base it will
stay blue
O If Red litmus paper is
dipped in a base it will
turn Blue
Question #2!
O What is the difference between the pH scale and
litmus paper?
Acid-Base Reactions:
Neutralization
O Neutralization Reaction: When acids and bases are mixed
together, they neutralize each other. If an equal
concentration of acid and base are mixed, they make a
neutral solution of a salt and water
H+
H+
O2-
O2-
H+
HCl + NaOH —> H2O + NaCl
Acid
Base
Water Salt
H+
Titration (Lab Process)
O The lab process where this is
studied is called titration
and it uses a piece of
glassware called a buret.
Acid Rain
O Acid Rain: Plants and animals
need water close to neutral (pH 7)
to survive.
O Due to pollution from industries
and cars, rain in certain areas can
be acidic. Rain less than pH 5.6 is
called acid rain.
O Acid rain can kill plants, cause
asthma, and other physical
problems.
O Because statues and landmarks
are made of limestone (a base),
acid rain will also slowly destroy
them.
Acid Rain (cont)
O The Roman ruins, the
pyramids of Egypt, and other
treasures of the world are
slowly being reacted away by
acid rain.
O More damage has been done
in the last century than in the
last 2,000 years.
Acid Rain (cont)
O Why do you think there has
been more damage from acid
rain in the last 100 years?
Let’s See What You Know…
Letter
B
D
C
A
Matching
1. Acid
2. Base
3. Neutral
4. Neutralize
A. To mix acids and bases to cancel each
other out and make water and salt
B. A compound that adds H+ ions to
water
C. Equal number of H+ and OH- ions;
water is an example
D. A compound that adds OH- ions to
water.
E
5. Acid Rain
E. When pollution causes rain to have a
pH less than 5.6.
F
6. pH
F. The measure of how acidic or basic a
solution is
H
7. Salt Water
G. A compound that adds a few OH- ions
to water
8. Strong Acid
H. The product of a neutralization reaction
between an acid and a base
G
9. Weak Base
I. A compound that adds a few H+ ions to
water
I
10. Weak Acid
J. A compound that adds a lot of H+ ions
to water.
J
Part II….
Is it an Acid or a Base?
Circle the acids and underline the bases
11. HCl
17. H2CO3
23. apple juice
12. Mg(OH)2
18. NaOH
24. lemonade
13. H3PO4
19. Al(OH)3
25. soap
14. KOH
20. HBr
26. laundry detergent
15. Ca(OH)2
21. H2SO4
27. soft drinks
16. LiOH
22. H2O
28. bathroom cleaner
Part III
Acids or Bases? Identify the
following with an
A for Acid or B for Base
29. pH of 1 to 7
30. Feels slippery
31. pH of 7 to 14
32. Has more OH- ions
33. Has more H+ ions
34. Tastes sour
A
B
B
B
A
A
TAKS Practice
1 A student wearing goggles, gloves, and an apron begins a simple activity to determine the pH
of corrosive solutions. Before the activity, what other safety measures should the student
follow?
A Identify the locations of eye wash, shower, and fire equipment
B Check and set clocks and record the beginning time
C Review the proper method of fire-polishing glass tubing
D Arrange the equipment in the work area alphabetically
TAKS Practice
2 Hard water has a pH higher than 7 and an abundance of calcium and magnesium salts. Which
of the following would be the best cleaning solution for removing hard-water residue from
drinking glasses?
A A mild acid such as vinegar
B A strong solution such as ammonia
C A hot solution such as baking soda in boiling water
D A strong base such as sodium hydroxide
TAKS Practice
3 Two clear solutions are placed in separate beakers. The first solution has a pH of 4, and the
pH of the second solution is unknown. If the two solutions are mixed and the resulting pH is 5,
the second solution must have –
A fewer suspended solids
B a lower temperature
C more dissolved salt (NaCl) particles
D a higher concentration of OH-ions
TAKS Practice
Properties of Some Solutions
Solution
Electrical
Conductivity of
Solution
Original Color of
Litmus Paper
1
2
3
4
Very high
Low
Moderate
Very high
Red
Blue
Red
Blue
Color of Litmus
Paper After
Dipping in
Solution
Blue
Red
Red
Red
pH
10.0
6.5
5.4
2.0
4 The table shows data from an investigation designed to find a liquid solution that is both an
acid and a strong electrolyte. Based on the data, a solution that is both an acid and a strong
electrolyte is –
A Solution 1
B Solution 2
C Solution 3
D Solution 4
Venn Diagram of Acids and
Bases
O At least 3 points
about Acids and
Bases
O At least 2 points
about what they
have in common