Properties of acids and bases








Sour/tart taste
Conduct electricity
Litmus turns red
Release H+ into
water
pH < 7
Neutralize a base
Usually start with H
Most food items








Slippery to the touch
Bitter taste
Conduct electricity
Litmus turns blue
Release OH- into
water
Neutralize an acid
pH > 7
Most cleaning items
An acid is a compound that gives H+ (or
H3O+) in water. Acids generally begin with H.
HCl + H2O  H3O+1 + Cl-1
HCl  H+1 + Cl–1
A base is a compound that gives OH- in
water. Bases usually end in –OH.
NaOH  Na+1 + OH-1
An indicator is a colored substance that can
exist in either an acid or base solution.
Two common indicators:
Litmus paper: red  blue
6.8  7.3
Phenolphthalein: clear  pink
8.3  8.4
Monoprotic: acids or bases that give off one
H+1(acid) or OH-1(base)
HCl  H+1 + Cl-1
NaOH  Na+1 + OH-1
Diprotic: acids or bases that give off two H+1
(acid) or two OH-1(base)
H2SO4  2 H+1 + SO4-2
Ca(OH)2  Ca+2 + 2OH-1
Triprotic: acids or bases that give off three
H+1(acid) or three OH-1(base)
H3PO4  3H+1 + PO4-3
Al(OH)3  Al+3 + 3 OH-1
Ions – charged particles
Naming acids
Common acids normally begin with H. When
you see a compound that begins with H, it
should be named as an acid. The name of the
acid depends on the negative ion:
•If the name of the anion ends in –ide
Hydro (anion without –ide) –ic acid
HCl – hydrochloric acid
HBr – hydrobromic acid
H2S – hydrosulfuric acid
•If the anion ends in –ate, everything is the
same except do not add the prefix hydro(anion name without –ate) –ic acid
HNO3 – nitric acid
HClO3 – chloric acid
H2SO4 – sulfuric acid
Common acids and bases







HCl
HNO3
H2SO4
HC2H3O2
HBr
H2CO3
H3PO4





NaOH
KOH
Ca(OH)2
Mg(OH)2
Ba(OH)2
Bronsted Acid-Bases
Acid – a substance that gives up H+
Conjugate Base – what is left after the acid
gives up H+
Base – a substance that gains H+
Conjugate Acid – what is left after the base
gains H+
Plain acids and bases are on the left side of
a reaction, the conjugate acid and base are
on the right side of a reaction.
C2H3O2-1 + NH4+1  HC2H3O2 + NH3
B
A
CA
CB
H2O + H3PO4  H3O+1 + H2PO4-1
B
A
CA
CB
H2O + NH3  OH-1 + NH4+1
A
B
CB
CA
HSO4-1 + C6H5-1  C6H6 + SO4-2
A
B
CA
CB
[ ] = concentration (unit of molarity)
In pure water at 25oC
[H+1] = 1.00 E-7 M
[OH-1] = 1.00 E-7 M
[H+1]x[OH-1] = 1.00E-7 x 1.00E -7 = 1.00E-14
One way of expressing the [H+1] or the
[OH-1] is the pH.
pH = -log[H+1]
pOH = -log[OH-1]
Important Formulas:
pH + pOH = 14.00
[H+1] x [OH-1] = 1.00 E-14
pH = -log[H+1]
pOH = -log[OH-1]
pH Scale
06.99
acid
7.00
neutral
7.01  14.00 base
To calculate the pH (or the pOH)
1.
(-)
2. log
3. [H+1] (or [OH-1]
To calculate [H+1] (or [OH-1])
1.
10x (2nd log)
2. (-)
3. pH (or pOH)
Strength of an Acid or Base
The strength of an acid (or base) is a measure of
how much they ionize or break up into ions in
water. The more they ionize, the stronger the acid
(or base).
The strength of an acid (or base) is measured by
the Ka or Kb. The larger the Ka (acid) or Kb (base)
the stronger it is. Most acids and bases are weak.
There are 6 strong acids and 4 strong bases:
Acids: H2SO4, HNO3, HClO4, HCl, HBr, HI
Bases: NaOH, KOH, Ca(OH)2, Ba(OH)2
All other acids and bases are considered weak.
Neutralization Reactions
An acid will react with a base and neutralize
each other. The result when they are mixed
is ALWAYS salt and water.
Acid + Base  Salt + Water
HA + BOH  BA + HOH
HCl + NaOH  NaCl + HOH
To predict the products of neutralization
reactions:
1. Recognize that it is a double replacement
reaction
2.Pair up the new products: one will always
be HOH (or water, H2O)
3.You can get the correct charges from H+1
or OH-1
4.Get the correct formulas by crossing the
charges
5.Balance the reaction
H2SO4 + Al(OH)3 
• H2SO4 + Al(OH)3  HOH + AlSO4
(pair up new products)
• H2SO4 + Al(OH)3  HOH + Al2(SO4)3
(get the correct formulas)
• 3H2SO4 + 2Al(OH)3  6HOH + Al2(SO4)3
(balance the reaction)
Titration – a solution of a known
concentration is reacted with a known
volume of a solution of unknown
concentration. At the endpoint, an indicator
will change colors. At that point,
the [H+1] = [OH-1]. From this information,
the unknown concentration can be
determined.
1. Write a balanced reaction
2. Label all numbers
3. Use unit analysis
4. Start with the volume of the compound
that you know both volume and
concentration
5. vol  moles A  moles B  conc B
27.5 milliliters of H2SO4 is exactly
neutralized by 39.3 milliliters of 0.437 M
NaOH. What is the concentration of the
acid?
H2SO4 + 2 NaOH  Na2SO4 + 2 HOH
Acid: 27.5 ml
Base: 39.3 ml
0.0393 L NaOH
0.437 M
0.437 mol NaOH
1 mol H2SO4
1 L NaOH
2 mol NaOH
1
=
0.0275 L H2SO4
0.312M H2SO4
There is an alternate way to do titration
calculations that does not involve writing
balanced reactions or unit analysis:
PLHABTSM®
M1V1P1 = M2V2P2
M1 = conc of acid
M2 = conc of base
V1 = volume of acid
V2 = volume of base
P1 = protacticity
P2 = protacticity
Protacticity
P1 = # of H+1 per molecules
P2 = # of OH-1 per molecules
1. Read the problem
2. Label all of the numbers
3. Identify the unknown
4. Use M1V1P1 = M2V2P2
5. Solve for the unknown
27.5 milliliters of H2SO4 is exactly
neutralized by 39.3 milliliters of 0.437 M
NaOH. What is the concentration of the
acid?
M1 = ?
M2 = 0.437 M
V1 = 27.5 ml
V2 = 39.3 ml
P1 = 2
P2 = 1
M1 = M2V2P2/V1P1
= (0.437 x 39.3 x 1)/(27.5 x 2)
= 0.312 M H2SO4