The titration of a weak acid with a strong base is a common exercise in chemistry labs. We have looked at all of the individual types of calculations needed to determine the pH at any point of a titration. Consider the titration of 0.100 L of 0.300 M acetic acid with 2.00 M NaOH. What type of calculation will we be performing at the following points of the titration curve

1. Weak acid calculation

2. Strong base calculation

3. Strong base calculation

4. Strong base calculation

Explanation:

1. Zero equivalents of base added  

2. 0.15 equivalents of base added  

3. One equivalent of base added  

4. 1.75 equivalents of base added

The equivalents of acetic acid are:

0.100L * (0.300mol/L) = 0.0300 moles of acetic acid = 0.0300Eq.

1. With Zero equivalents of base added you will calculate pH using weak acid calculation because you have only acetic acid (Weak acid) in the solution.

2. When 0.15 equivalents of base are added all the acid reacted and 0.15-0.03 = 0.12 equivalents of Strong base are in excess. With these equivalents and the volume we can find pH using strong base calculation.

3 and 4. As with 0.15 eq. added the 1 eq. and 1.75 eq. produce an excess of strong base and the pH must be calculated by using strong base calculation