Acids and Bases
Arrhenius Acid & Base
Which beaker contains a base?
Bronsted Lowry Acid and Base
• Acid is a proton donor
• HF + H2O  H3O+ + F• Base is a proton
acceptor
NH3 + H30+  NH4++H20
Conjugate acid base pairs
Fill in the following table with the
appropriate conjugate acid or base
Acid
H2SO4
Base
PO43-
NH4+
F-
H20
H20
Polyprotic acid
•
•
•
•
Monoprotic
HCl, ClDiprotic
H2S, HS-, S2Diprotic
H2SO4, HSO4-, SO42Triprotic
H3PO4, H2PO4-, HPO42-, PO43-
Naming acids
• Binary acids
• Hydro ____________ ic acid
• Ternary acids
• ______________ ic acid
• ______________ous acid
Name the following acids
•
•
•
•
•
•
H2S (aq)
H2SO3
HClO2
HNO3
HF(aq)
HC2H3O2
Strong acids completely ionize in water
Strong acids (memorize)
Strong acids:
Completely
ionize in water
Weak acids in water
are in equilibrium
They don’t completely
Ionize in water
Bases
donate OHor accept H+
•
•
•
•
•
NaOH
Mg(OH)2
Al(OH)3
NH3
PO43-
Neutralization reactions
Acid + base react to form salt + water
HCl + NaOH  NaCl + H2O
H2SO4 + 2NaOH Na2SO4 + 2 H2O
How many moles of phosphoric acid are needed
to react with 5.0 moles of sodium hydroxide?
Identify each of the following as an
acid, base or salt
Acid
HC2H3O2
MgCl2
H2SO4
Ca3(PO4)2
Sr(OH)2
Al(NO3)3
Base
Salt
Complete the following neutralization
reactions and balance
• HBr + NaOH 
 CaCl2 + H2O
 Sr3(PO4)2 + H2O
pH=-log H3
+
O
Equations to determine pH
•
•
•
•
Kw = [H30+][OH-]
Kw = 1x10-14
pH = -log [H3O+]
[H30+] = 10 –pH
Fill in the following graph
pH
[H3O+]
[OH-]
6.60
1.8 x 10-3
2.91
3.89 x10-2
5.9 x 10-6
13.12
Acid/base?
pH
[H3O+]
[OH-]
Acid/base?
6.60
2.51 x 10-7
4.0x10-8
acid
11.1
5.6x10-12
1.8 x 10-3
base
2.91
1.23 x 10-3
8.13 x 10-12 acid
1.41
3.89 x10-2
2.57 x 10-13 acid
8.8
1.7 x 10-9
5.9 x 10-6
base
13.12
7.59 x 10-14
0.13
base
compound
H3O+
0.00000510 M
HNO3
6.69x10-2 M
KOH
_____M HCl
OH -
pH
2.3
Stomach produces HCl, how does it
protect itself?
The acid in the stomach is hydrochloric acid, HCl,
and has a pH of about 2.
Acid of pH 2 can be quite corrosive - observe the
effect of placing an iron nail in hydrochloric acid
solution with pH =2
Buffer
• Buffer resists change in pH when small
amounts of acid or base are added
• A buffer is a solution containing either
a weak acid and its salt or a weak
base and its salt,
• Weak acid + its salt is the acid and its
conjugate base
Buffer system
Weak acid
Salt of the acid
(conjugate base)
A Buffer consists of
HSO4-
and
NaOH is added to the solution.
Who is the shark?
SO42-
Did you pick HSO4-?
• Write the reaction
A Buffer consists of
H2CO3
and
HCl is added to the solution.
Who is the shark?
HCO3-
Predict whether each pair would form
a buffer. Explain your answer.
Pairs of
compounds
KOH, KCl
HI, NaI
NH4I, NH3
NaH2PO4,
H3PO4
Explanation
Write an equation showing the buffering
action of each of the following aqueous
solutions
• NH4I / NH3 adding OH• NaH2PO4/H3PO4 adding H3O+
Buffers in the body
The body has many systems to control pH of
the blood