“When a strong base is graduallyadded dropwise to a weak acid, the pH changes at each addition.When the appropriate quantity of base has been added to react withall of the acid, the pH changes sharply, indicating the endpoint ofthe titration. A plot of pH versus volume of base added gives whatis known as a titration curveâ€.
Consider the titration of 25.00 mLof 0.1000 M benzoic acid with 0.1000 M NaOH,.
Write a balanced chemical equationfor the titration reaction using C6H5COOH for benzoic acid’sformula.
Determine the volume of NaOH solution required to reach theendpoint.
The chart on the next page hasentries for several steps along the titration curve. To calculatethe pH at each step, you first must understand the chemistry atthat step, and then you can decide the appropriate method tocalculate the pH. For each volume listed, (i) list the majorspecies in solution, (ii) determine whether the Ka equation, Kbequation, buffer equation, or solution equilibrium equation isappropriate for the calculation of the solution [H3O+] and pH, and(iii) complete the calculations.
Volume NaOH Added (mL) | Major Species | Appropriate Equation | [H3O+] | pH |
0.00 | | | | |
5.00 | | | | |
12.50 | | | | |
20.00 | | | | |
25.00 | | | | |
30.00 | | | | |
