1
This document contains extra practice problems involving equilibrium, acid/base, buffer, and
titration calculations. The exam will also include short answer conceptual questions on these topics.
1.
A 0.0560 g quantity of CH
3
COOH is dissolved in enough water to make 50.0 mL of
solution. Calculate the concentrations of H
+
, CH
3
COO

and CH
3
COOH at equilibrium.
K
a
=1.8 x 10
5
.
CH
3
COOH=60 g/mol
0.0560 g=9.33 x 10
4
mol
9.33 x 10
4
mol/0.050 L=0.01867 M CH
3
COOH
CH
3
COOH
CH
3
COO

H
3
O
+
I
0.01867
0
0
C
x
+x
+x
E
0.01867x
x
x
Ka=[ CH
3
COO

][ H
3
O
+
]/[CH
3
COOH]
X=5.786 x 10
4
[H
3
O
+
]=[ CH
3
COO

]=5.786 x 10
4
M
[CH
3
COOH]=0.0181 M
2.
A titration in conducted where exactly 500 mL of 0.167 M NaOH was titrated into 500 mL
0.100 M CH
3
COOH. Calculate the pH of the solution at this point in the titration.
CH
3
COOH Ka=1.8 x 10
5
.
Initial moles
NaOH: 0.5 L x 0.167 mol/L=0.0835 mol
CH
3
COOH
: 0.5 L x 0.10 mol/L=0.050 mol
CH
3
COOH
+

OH
Æ
CH
3
COO

+ H
2
O
All acid is neutralized, 0.0335 mol

OH remaining
0.0335 mol/L=0.0335 M
pOH=1.47
pH=12.53
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