1. Acid-Base Reactions

2. Titrations can be used in the analysis of
Acid-base reactions
Redox reactions
H2SO4 + 2NaOH H2O + Na2SO4
5Fe2+ + MnO4- + 8H Mn Fe3+ + 4H2O

3. Neutralization Reaction
acid + base salt + water
HCl (aq) + NaOH (aq) NaCl (aq) + H2O
H+ + Cl- + Na+ + OH Na+ + Cl- + H2O
net ionic equation
for strong acids
and strong bases
H+ + OH H2O

4. Titrant or Standard Solution (known concentration)
Analyte (unknown concentration)
stopcock
Titration
In a titration, a solution of accurately known concentration (standard) is added gradually added to another solution of unknown concentration (analyte) until the chemical reaction between the two solutions is complete.

5. Titration vocab mol H+ = mol OH-
Equivalence point – the point at which the moles are equal
mol H+ = mol OH-
Indicator – substance that changes color at (or near) the end point
End point—the point which the indicator used in titration changes color

7. When doing a titration…
Be sure to add the indicator used in titration changes color and measure your titrant each run.
Slowly add base
to unknown acid
UNTIL
the indicator
changes color
(pink)

8. Strong Acid-Strong Base Titrations
NaOH (aq) + HCl (aq) H2O (l) + NaCl (aq)
OH- (aq) + H+ (aq) H2O (l)

9. The titration curve of a strong acid with a strong base.

10. Weak Acid-Strong Base Titrations
CH3COOH (aq) + NaOH (aq) CH3COONa (aq) + H2O (l)
CH3COOH (aq) + OH- (aq) CH3COO- (aq) + H2O (l)
At equivalence point (pH > 7)

12. Example 1
9.50 mL of M NaOH was needed to titrate 5.89 mL of nitric acid. Calculate the molarity of the acid.

13. 2RbOH(aq) + H2SO4(aq) → 2H2O(l) + Rb2SO4(aq)
Example 2
In a titration, mL of a M RbOH solution is required to exactly neutralize mL of sulfuric acid. What is the molarity of the sulfuric acid solution?
2RbOH(aq) + H2SO4(aq) → 2H2O(l) + Rb2SO4(aq)
43.21 mL RbOH
1 L
mol RbOH
1 mol H2SO4
= mol H2SO4
1000 mL
2 mol RbOH
mol H2SO4
1000 mL
= M H2SO4
30.00 mL
1 L

14. The perfect endpoint color for phenolphthalein is light pink.

15. This is one drop beyond the perfect equivalence point light pink.

16. Well beyond the perfect equivalence point light pink.