Cliffs AP Chemistry, 3rd Edition

(e) Given: 0.500 liter = volume

035. M=+6@NaC H O 232 "Na+ C H O 232 -

[HA] = 0.50 M

1.5 g LiOH added to solution

.

..

g LiOH

g LiOH

mole LiOH mole LiOH

1

15

23 95

#^1 =0 063

Restatement: pH =?

Step 1: Write a balanced equation expressing the reaction betweeen acetic acid and lithium
hydroxide.

HA + OH–→A–+ H 2 O

Step 2: Create a chart that expresses initial and final concentrations (at equilibrium) of the
species.

Species Initial Concentration Final Concentration

HA 0.50 M..

050. .M

0 500

-=0 063 0 375

A– 0.35 M 035. +=0 5000 063.. 0 475.M

Step 3:Write an equilibrium expression for the ionization of acetic acid.

.

.

.

.

HA

HA H

HM

174 10

0 374

048

137 10

a^5

5

#

#

== =

=

• 
  
  
  
  • 
    
  
  
  
  


• 
  

++

+

K

6

77

6

7 6

7

@

AA

@

A @

A

Step 4:Solve for the pH.

pH = −log[H+] = −log (1.37 × 10 –5) = 4.86

Part II: Specific Topics