Why is Eriochrome Black T used in EDTA titration?

When used as an indicator in an EDTA titration, the characteristic blue end-point is reached when sufficient EDTA is added and the metal ions bound to the indicator are chelated by EDTA, leaving the free indicator molecule. Eriochrome Black T has also been used to detect the presence of rare earth metals.

What is the color change of Eriochrome Black T in EDTA titration?

EDTA is short for ethylenediaminetetraacetic acid. A blue dye called Eriochrome Black T (ErioT) is used as the indicator. This blue dye also forms a complex with the calcium and magnesium ions, changing colour from blue to pink in the process.

What is the meaning of T in Eriochrome Black T?

In reactive dyes for cotton, M denotes a warm- (ca 40 °C) dyeing dye, and H is a hot-dyeing (ca 80 °C) dye. So, “T” is likely a code for a color (no colors come to mind) or for some other property. The Eriochrome trademark is registered to Huntsman Petrochemical. Of the dyes listed on their site, some are labeled “TS”.

Why is Eriochrome Black T used to determine the hardness of water?

In this experiment the indicator eriochrome black T (EBT) is used to signal the presence of ions in the water sample. EBT binds with free metal ions in the water to form a pink complex.

Which colour appears at the end of EDTA titration?

The endpoint of a complexometric EDTA titration using either Calmagite or EBT as the indicator is detected as the colour changes from pink to blue.

Why is the indicator eriochrome black EBT shows wine red color at the beginning and blue color at the end?

Answer: As the stronger ligand EDTA is added, the CaIn+(aq) complex is replaced by the CaY2-(aq) complex which is blue. The end point of titration is indicated by a sharp colour change from wine red to blue. Titration using Eriochrome Black T as indicator determines total hardness due to Ca2+(aq) and Mg2+(aq) ions.

What is the composition of Eriochrome Black T indicator?

40% Ethanol/60% Triethanolamine Composition: Triethanolamine 67.57%, Ethyl Alcohol 28.62%, Isopropyl Alcohol 1.58%, Methyl Alcohol 1.43%, Eriochrome Black T 0.80% Density: 1 Color: Dark blue liquid Physical State: Liquid Solubility Information: Miscible Shelf Life: 6 Months Storage:…

What is the structure of Eriochrome Black T?

C20H12N3O7SNaEriochrome Black T / Formula

How does EDTA remove water hardness?

EDTA is polyprotic acid which contains four carboxylic groups and two amines with lone pair electrons. It is able to form stable complexes with water to remove its hardness because Mg+2 and Ca+2 react with this ligand to form complexes.