Page 53 - Analytical Chemistry I E-book

Acid-Base Titration Curves

• Definition: A titration curve is a plot of the pH of the titrated solution (sample
solution) as a function of the volume of titrant added.

• The shape of a titration curve depends upon:
1- Nature of sample and titrant.
2- Concentrations of sample and titrant.
3- pK values if the analyzed sample was a

weak acid or weak base.

• Significance:

1- It indicates the feasibility of titrations. There must be a

sufficiently sharp break in the pH at the equivalence point.

2- It helps in proper selection of indicator and

determination of end point.

• To construct a titration curve, it is convenient to calculate the pH of the sample

solution in four distinct parts:

1- Before beginning titration.

2- After adding the titrant and before reaching the

equivalence point. 3- At the equivalence point.

4- After the equivalence point.