Example Answers (on handout)
Soluble or Insoluble?
7.
8.
9.
10.
11.
12.
K
Fe
3
PO
3
(PO
PbCl
2
4
FeSO
4
(NH
4
)

4
)
Soluble
2
 Insoluble
 Insoluble (exception)
 Soluble
2
S  Soluble (exception)
PbS  Insoluble

• L A B T H I S W E E K - A N A L Y S I S O F S I L V E R
G R O U P I O N S
• O W L H O M E W O R K - N E W A S S I G N M E N T S
P O S T E D
•
ACID-BASE, SOLUBILITY, NET IONIC EQUATIONS

Which of the following is soluble?
1.
2.
3.
4.
AlPO
4
PbBr
2
Al(OH)
3
FeSO
4
10%
47%
29%
14%
1 2 3 4

Which of the following is insoluble?
1.
2.
3.
4.
Al(NO
3
)
3
PbC
2
O
4
NaOH
FeF
3
24%
5% 10%
1 2 3 4
61%

pH Review
 What is the pH of a 0.25M solution of NaOH?
 pH + pOH = 14 pOH=-log[OH ]

NaOH is a strong base  [NaOH]=[OH ] pOH= -log[0.25]=0.602
pH= 14 - pOH = 14 = 0.602 = 13.4

What is the [H
3
O + ] of this solution?

[H
3
O + ] = 10 -pH = log -1 (-pH)
[H
3
O + ] = 10 (-13.4) = 3.98 x 10 -14 M

Conjugate Acid-Base Pairs
 Anions of weak acids are weak bases

Conjugate acids and conjugate bases
Weak Acid

Example:
CH
3
COOH = weak acid
CH
3
COO = weak base
What would this look like in a reaction?
CH
3
COOH
NH
4
+
H
2
CO
3
H
2
C
2
O
4
H
2
SO
3
CH
3
COONa + HCl  ?
H
2
S
H
3
PO
4
HCN

Anions of strong acids are neutral
HF
NHO
2
HClO
Weak Base
CH
3
COO -
NH
3
CO
3
2-
C
2
O
4
2-
SO
3
2-
S 2-
PO
4
3-
CN -
F -
NO
2
-
ClO -

Conjugate Acids and Bases- More Examples
 HCl + NaCN  ?
 HNO
3
+ AlPO
4
 ?

Net Ionic Equations
1.
3.
Write all reactants as they exist in solution
2.

Identify acids and bases
Need both acid and base present

Look for “hidden bases” (anions of weak acids)
Ions that form insoluble compounds will form precipitates
4.
5.
6.
Look for known gas-forming reactions
Write out the products as they exist in solution
Cancel spectator ions

Precipitation Reactions
Net Ionic Equations
Pb(NO
3
)
2
+ K
2
CrO
4
 ?
Pb(NO
3
)
2
+ KI  ?
Ba(NO
3
)
2
+ Na
2
C
2
O
4
 ?

Gas Forming Reactions
 Special class of acid-base reactions
Gas Forming Reactions
2H + + CO
3
2 H
2
O(l) + CO
2
(g)
2H + + S 2 H
2
S(g)
2H + + SO
3
2 H
2
O(l) + SO
2
(g)
2H + + M  M 2+ + H
2
(g)
 Combination of double displacement (swap) and decomposition reactions

2HCl + Na
2
CO
3
 ?