Titration curve

Titration Curve

A titration curve is a graphical representation of the pH of a solution as a function of the volume of titrant added during a titration. It is an essential tool in analytical chemistry for determining the concentration of an unknown solution.

Titration curve of oxalic acid

Types of Titration Curves

Titration curves can vary depending on the type of titration being performed. The most common types include:

Strong Acid-Strong Base Titration

In a strong acid-strong base titration, the titration curve typically shows a sharp change in pH at the equivalence point. This is because both the acid and base dissociate completely in solution.

Weak Acid-Strong Base Titration

For a weak acid-strong base titration, the curve is more gradual, with a less pronounced equivalence point. This is due to the partial dissociation of the weak acid.

Weak Base-Strong Acid Titration

Similarly, in a weak base-strong acid titration, the curve is gradual, reflecting the partial dissociation of the weak base.

Polyprotic Acid Titration

Polyprotic acids, such as oxalic acid, have more than one dissociable proton, resulting in multiple equivalence points on the titration curve.

Features of a Titration Curve

A typical titration curve has several key features:

Initial pH

The initial pH of the solution before any titrant is added.

Buffer Region

In the case of weak acids or bases, a buffer region is observed where the pH changes slowly.

Equivalence Point

The point at which the amount of titrant added is stoichiometrically equivalent to the amount of substance in the solution. This is often marked by a steep change in pH.

End Point

The point at which the indicator changes color, which should ideally coincide with the equivalence point.

Final pH

The pH of the solution after excess titrant has been added.

Applications

Titration curves are used in various applications, including:

• Determining the concentration of an unknown solution.
• Identifying the pKa of a weak acid or base.
• Analyzing the purity of a substance.

Related Pages

• Acid-base titration
• pH
• Buffer solution
• Equivalence point