1. Neutralization of Acids and Bases

2. Primary Standard with a
Titrations
Primary Standard with a
precisely known [ ]
Burette
1st titration
Standard
Solution
Known [ ]
Standard Solution
2nd titration
How do we accurately know the [ ] of a standard solution?
Ie. NaOH is hygroscopic and we are unable to accurately determine its concentration in order to make a standard solution.
So, we use a primary standard which has the following characteristics:
pure & stable
non-hygroscopic
accurately known molar mass
Examples: Na2CO3
KHC8H4O4 (pottasium hydrogen phthalate)
C6H5COOH (benzoic acid)
Which one to use? Depends if your standard is an acid or a base - must use the opposite one to do a preliminary titration.
Sample Solution
Unknown [ ]
Sample Solution

3. ACID + BASE WATER + SALT
In general, a titration involves the addition of either a strong acid, strong base or both (must go to completion) as follows:
ACID + BASE WATER + SALT
Titrations do not always yield an equivalence point with a pH of 7. Why?
The salts produced may further hydrolyze to change the equivalence to either acidic or basic

4. Choosing Indicators For Titrations
will depend on the overall pH of the salt produced

5. Strong Acids and Strong Base Titrations
Example: HCl (strong acid) and NaOH (strong base)
Formula Equation:__________________________________
Complete Ionic Equation: ____________________________
Net Ionic Equation:__________________________________
pH at equivalence point: _____________________________
Possible Indicators:__________________________________

6. Titration Curve for Strong Acid & Strong Base
pH of sample
solution is
very low SA
Base is the standard
solution being added

7. Strong Acid & Strong Base4 3 2 1

8. How are the pH’s calculated at the various stages. Eg. 40. 0 mL of 0
How are the pH’s calculated at the various stages? Eg mL of M HCl is titrated with M NaOH.
The initial acid concentration? 1
NaOH is added (eg mL) but acid is in excess? 2
Equivalence point? 3
Base is in excess (eg mL added)? 4

9. Weak Acids and Strong Base
Titrations
Example: CH3COOH (weak acid) and NaOH (strong base) Formula Equation:__________________________________ Complete Ionic Equation: ____________________________ Net Ionic Equation:__________________________________ pH at equivalence point: _____________________________ Possible Indicators:__________________________________

10. Weak Acid & Strong Base E.P > 7 pH starts higher as CH3COOH is
a weaker acid

11. Weak Base and Strong Acid Titrations
Example: NH3 (weak base) and HCl (strong acid) Formula Equation:__________________________________ Complete Ionic Equation: ____________________________ Net Ionic Equation:__________________________________ pH at equivalence point: _____________________________ Possible Indicators:__________________________________

12. Weak Base & Strong Acid Sample of Strong Base E.P < 7
Standard Acid is added

13. Three types of Titrations:

14. Choosing an Indicator:

15. Monoprotic Acids When the mole ratio of acid to bases is 1:1,
then they will require equal volumes to reach equivalence point
Acid and Base strength is irrelevant
Example: A strong acid requires an equal volume of weak base
to reach equivalence point if they each have a coefficient of 1

16. Polyprotic Acids
When an acid releases more than one proton, ie. H2SO4,
then they will require twice the volume of base to
reach equivalence point

17. Titration of a polyprotic acid: one equivalence point per acidic hydrogen