JoVE Core

Analytical Chemistry

A subscription to JoVE is required to view this content.

live

Speed

×

MEDIA_ELEMENT_ERROR: Format error

5.9 : Complexometric EDTA Titration Curves

EDTA titration curves determine the free metal ion concentration. The titration curve represents the change in concentration of free metal ions (p function) as a function of the volume of EDTA added. This curve consists of three regions: before, at, and after equivalence points. Excess free metal ions are present before the equivalence point. Equal concentrations of metal ions and EDTA are present at the equivalence point. After the equivalence point, excess EDTA exists. This means slight dissociation can be observed at and after the equivalence point.

The complex's conditional formation constant (Kf′) calculates the free metal ion concentration at and after the equivalence point, and the shape of the titration curve is affected by Kf′ of the complex. For example, the Ca–EDTA complex has a larger Kf′ than the Sr–EDTA complex. As a result, the Ca–EDTA titration curve has a larger break at the equivalence point.

The Kf′ of the complex depends on the pH of the solution. For instance, Ca–EDTA exhibits various shapes at different pH. At higher pH, Ca–EDTA has a larger Kf′, and complex formation is more favorable. The curve has a large break at the equivalence point. At lower pH, the Kf′ of the complex is small, indicating less favorable complex formation. As a result, the curve has a small break at the equivalence point.

From Chapter 5:

article

Now Playing

5.9 : Complexometric EDTA Titration Curves

Complexometric Titration, Precipitation Titration, and Gravimetry

689 Views

article

5.1 : Complexometric Titration: Overview

Complexometric Titration, Precipitation Titration, and Gravimetry

4.1K Views

article

5.2 : Complexometric Titration: Ligands

Complexometric Titration, Precipitation Titration, and Gravimetry

783 Views

article

5.3 : Properties of Organometallic Compounds

Complexometric Titration, Precipitation Titration, and Gravimetry

814 Views

article

5.4 : EDTA: Chemistry and Properties

Complexometric Titration, Precipitation Titration, and Gravimetry

1.5K Views

article

5.5 : EDTA: Conditional Formation Constant

Complexometric Titration, Precipitation Titration, and Gravimetry

608 Views

article

5.6 : EDTA: Auxiliary Complexing Reagents

Complexometric Titration, Precipitation Titration, and Gravimetry

486 Views

article

5.7 : EDTA: Direct, Back-, and Displacement Titration

Complexometric Titration, Precipitation Titration, and Gravimetry

1.9K Views

article

5.8 : EDTA: Indirect and Alkalimetric Titration

Complexometric Titration, Precipitation Titration, and Gravimetry

628 Views

article

5.10 : Effects of EDTA on End-Point Detection Methods

Complexometric Titration, Precipitation Titration, and Gravimetry

206 Views

article

5.11 : Masking and Demasking Agents

Complexometric Titration, Precipitation Titration, and Gravimetry

2.1K Views

article

5.12 : Precipitation Titration: Overview

Complexometric Titration, Precipitation Titration, and Gravimetry

3.8K Views

article

5.13 : Precipitation Titration Curve: Analysis

Complexometric Titration, Precipitation Titration, and Gravimetry

897 Views

article

5.14 : Precipitation Titration: Endpoint Detection Methods

Complexometric Titration, Precipitation Titration, and Gravimetry

1.3K Views

article

5.15 : Gravimetry: Overview

Complexometric Titration, Precipitation Titration, and Gravimetry

3.4K Views

See More

We use cookies to enhance your experience on our website.

By continuing to use our website or clicking “Continue”, you are agreeing to accept our cookies.

Learn More