A complexometric indicator is an ionochromic dye that undergoes a definite color change in the presence of certain metal ions. It forms a weak complex with ions present in the solution, which has significantly different shades of the existing shape outside the complex. The complexometric indicator is also known as the pM indicator.
Video Complexometric indicator
Complexometric titration
In analytical chemistry, complexometric indicators are used in the titration of complexometry to show the exact moment when all metal ions in the solution are sequestered by the chelating agent (mostly EDTA). The indicator is also called metallochromic indicator .
The indicator may be present in another liquid phase in equilibrium with the titration phase, the indicator is described as the extraction indicator .
Some complexometric indicators are sensitive to air and destroyed. When the solution loses color during the titration, one or two new indicator drops may need to be added.
Maps Complexometric indicator
Example
The complexity indicator is a water-soluble organic molecule. Some examples are:
- Calcein with EDTA for calcium
- Curcumin for boron, which forms Rosocyanine, although the red change in curcumin also occurs for pH & gt; 8.4
- Eriochrome Black T for calcium, magnesium, and aluminum
- Fast Sulphon Black with EDTA for copper
- Hematoxylin for copper
- Murexide calcium and rare earths
- Xylenol orange for gallium, indium and scandium
Redox indicator
In some settings, when the titration system is a redox system whose equilibrium is affected by the removal of metal ions, the redox indicator can function as a complexometric indicator.
References
Source of the article : Wikipedia
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