Titration of Mono and Di-Protic Acids

Summary

This demonstration can also be used to compare monoprotic and diprotic acids.

Hazards

The solutions in this demonstration can cause burns. Avoid contact.

Chemicals and Solutions

• 1M HCl
• 1M H2SO4
• 1M NaOH
• Thymol blue indicator

Materials

• Two (size) burets
• Two 125mL Erlenmeyer flasks
• One 100 mL graduated cylinder

Procedure

1. Add several drops of thymol blue indicator to each of the acid solutions and the base solution.
2. Fill each buret with an acid and label them accordingly.
3. Measure out 40 mL of NaOH solution into each of the Erlenmeyer flasks.
4. Titrate the NaOH with each acid (the equivalence point is yellow).

Discussion

This demonstration shows the stoichiometry of the following reactions:

$\mathrm{HCl}{\phantom{A}}_{(\mathrm{aq})}+\mathrm{NaOH}{\phantom{A}}_{(\mathrm{aq})}⟶\mathrm{NaCl}{\phantom{A}}_{(\mathrm{aq})}+\mathrm{H}{\phantom{A}}_2\mathrm{O}{\phantom{A}}_{(\mathrm{l})}$

$\mathrm{H}{\phantom{A}}_2\mathrm{SO}{\phantom{A}}_4{\phantom{A}}_{(\mathrm{aq})}+2\mathrm{NaOH}{\phantom{A}}_{(\mathrm{aq})}⟶\mathrm{NA}{\phantom{A}}_2\mathrm{SO}{\phantom{A}}_4{\phantom{A}}_{(\mathrm{aq})}+2\mathrm{H}{\phantom{A}}_2\mathrm{O}{\phantom{A}}_{(\mathrm{l})}$