Titration Curve Essay

A titration curve is a plot of pH of the analyte solution versus volume of titrant added, as the titration progresses. 9,12 The equivalence point is the inflection point of a titration curve.9

Titration Curve showing a Strong Base being added to a Strong Acid

The pH of the analyte, in this case a strong acid like HCl, is plotted against the volume of the strong base, NaOH, that is being added. The titration of a strong acid with a strong base produces a titration curve as above.

Initially, before any NaOH is added, the pH of HCl is low because it contains mainly H3O +. As NaOH is added, H3O+ is slowly used by OH- because of dissociation of NaOH. The analyte remains acidic but the pH starts to increase as more NaOH is added.

The equivalence point is halfway up the steep curve and for a strong acid- strong base titration curve is

The titration of a weak acid with a strong base produces a titration curve as above.

Initially, before any NaOH is added, the pH of H2C2O4 .2H2O is low because it contains mainly H3O+. The starting pH will, however, be higher for a weak acid, like H2C2O4 .2H2O, than for a strong acid. As NaOH is added, H3O+ is slowly used by OH- because of dissociation of NaOH. The analyte remains acidic but the pH starts to increase as more NaOH is added.

The equivalence point is halfway up the steep curve and for a weak acid- weak base titration, the pH is NOT neutral at the equivalence point, but approximately 8.

As more NaOH is added, the pH will become more basic as H2C2O4 .2H2O has been completely neutralized and now an excess of OH- ions are present in the solution.12

Hydrochloric acid (HCl):

Hydrochloric acid is a strong and corrosive acid that is often used as a reagent in laboratories.

It is made by dissolving hydrogen chloride in water.