Copyright © Glencoe/McGraw-Hill, a division of The McGraw-Hill Companies, Inc.
Solving Problems: A Chemistry Handbook
Chemistry: Matter and Change
191
SOLVING PROBLEMS:
A CHEMISTRY HANDBOOK
CHAPTER 18
weak base titration. The following example problem shows you how
to use titration data to determine the concentration of a solution.
Example Problem 18-6
Calculating Concentration from Titration Data
In a titration, 53.7 mL 0.100M HCl solution is needed to neutralize
80.0 mL of KOH solution. What is the molarity of the KOH
solution?
Write the balanced equation for the neutralization reaction.
HCl(aq) ϩ KOH(aq) 0 KCl(aq) ϩ H 2 O(l)
Convert milliliters of HCl solution to liters.
53.7 mL HCl ϫ
ϭ 0.0537 L HCl
Determine the moles of HCl used by multiplying the volume of the
solution by its molarity, or mol/L.
0.0537 L HCl ϫ
ϭ 5.37 ϫ 10 Ϫ3 mol HCl
Use the mole ratio in the balanced chemical equation to calculate the
moles of KOH in the unknown solution.
5.37 ϫ 10 Ϫ3 mol HCl ϫ
ϭ5.37 ϫ 10 Ϫ3 mol KOH
Convert milliliters of KOH solution to liters.
80.0 mL KOH ϫ
ϭ 0.0800 L KOH
Determine the molarity of the KOH solution by dividing the moles
of KOH that reacted by the volume of the KOH solution in liters.
M KOH ϭ
ϭ 6.71 ϫ 10 Ϫ2 M
The molarity of the KOH solution is 6.71 ϫ 10 Ϫ2 M, or 0.0671M.
Practice Problems
11. A 45.0-mL sample of nitric acid solution is neutralized by
119.4 mL 0.200M NaOH solution. What is the molarity of the
nitric acid solution?
5.37 ϫ 10 Ϫ3 mol KOH
ᎏᎏᎏ
0.0800 L KOH
1 L KOH
ᎏᎏ
1000 mL KOH
1 mol KOH
ᎏᎏ
1 mol HCl
0.100 mol HCl
ᎏᎏ
1 L HCl
1 L HCl
ᎏᎏ
1000 mL HCl