Titrations

1
Titrations

• - Controlled addition and measurement of the
  amount of a solution of known concentration that
  is required to react with a measured amount of a
  solution of unknown concentration.

2
Important Terms and Concepts

• Standard solution
• solution of known concentration.
• Indicators
• weak acid or weak base dyes that are sensitive
  to pH (hydronium ion concentration).
• Equivalence point
• The point at which the two solutions used in a
  titration are present in chemically equivalent
  amounts.
• For our purposes, H3O OH-
• (moles of Acid moles of Base)

3
Practice Titration Problems

• 1) It requires 27.4mL of a standard solution of
  0.0154M Ba(OH)2 to completely neutralize 20.0mL
  of an HCl solution. Find the molarity of the acid.

Since we are switching substances STOICHIOMETRY!!
!!
?
27.4mL Base
0.0274L Base
Mole-to-mole using balanced equation!
2 HCl Ba(OH)2 ? BaCl2 2 H2O
Start bridge with volume of known solution.
20.0mL Acid
0.0200L Acid
0.0274L Base
0.0154 mol Ba(OH)2
2 mol HCl
?
1 LBase
1 mol Ba(OH)2
0.0200LAcid
0.0422M HCl
4
Practice Titration Problems

• 2) What volume of 1.25M potassium hydroxide is
  required to neutralize 25.0mL of 12.0M sulfuric
  acid?

? mL Base
Mole-to-mole using balanced equation!
2 KOH H2SO4 ? K2SO4 2 H2O
25.0mL Acid
0.0250L Acid
Start bridge with volume of known solution.
0.0250L Acid
12.0 mol H2SO4
2 mol KOH
1 LBase
1 LAcid
1 mol H2SO4
1.25 mol KOH
0.480 L Base
480. mL KOH
5
Practice Titration Problems

• 3) 17.6mL of H2SO4 is neutralized by 27.4 mL of
  0.0165M LiOH solution. Find the molarity of the
  acid.

Mole-to-mole using balanced equation!
?
H2SO4 2 LiOH ? Li2SO4 2 H2O
17.6mL Acid
0.0176L Acid
Start bridge with volume of known solution.
27.4mL Base
0.0274L Base
0.0274L Base
0.0165 mol LiOH
1 mol H2SO4
?
1 LBase
2 mol LiOH
0.0176LAcid
0.0128M H2SO4
6
Practice Titration Problems

• 4) It requires 15.5mL of a standard solution of
  0.215M KOH to completely neutralize 21.2mL of an
  HCH3COO solution. Find the molarity of the acid.

Mole-to-mole using balanced equation!
?
HCH3COO KOH ? KCH3COO H2O
15.5mL Base
0.0155L Base
Start bridge with volume of known solution.
21.2mL Acid
0.0212L Acid
0.0155L Base
0.215 mol KOH
1 mol HCH3COO
?
1 LBase
1 mol KOH
0.0212LAcid
0.157M HCH3COO