Why ebt is used as indicator?

The formation of a colored complex serves as an indicator of the endpoint of the titration. It can be used in determining the hardness of water using eriochrome black T as an indicator. Eriochrome black T is an azo-dye and contains a functional group of two nitrogen atoms joined by a double bond.

What is the use of EBT indicator?

Eriochrome Black T is a complexometric indicator that is used in complexometric titrations, e.g. in the water hardness determination process. It is an azo dye. Eriochrome is a trademark of Huntsman Petrochemical, LLC. In its deprotonated form, Eriochrome Black T is blue.

Why is EBT a solid indicator?

The complexing agent binds to the metals and, after all the metals have been complexed, the next drop of complexing agents binds to an indicator to induce a color change. … Eriochrome black T, or EBT, represents one of the color-changing compounds for such titrations.

Why is EBT used as an indicator in determining water hardness?

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. If the indicator turns from blue to pink, metal ions such as calcium and magnesium are present. …

Why EBT and EDTA are used and not methyl orange?

Because phenolphthalein is an acid-base indicator (responds to pH) whereas EDTA titration is not an acid base one, but operates on a different principle. In fact it is usual to buffer the mixture to keep the pH approximately constant (at about pH 10 for Eriochrome Black T indicator).

What is the colour of EBT indicator?

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.

Why do we add buffer solution during titration?

A buffer solution is used in EDTA titration because it resists the change in pH. This is because all the reactions between the metal ions and EDTA are pH-dependent.

Which buffer solution is used before adding EBT?

On addition of EDTA solution, Ca2+/Mg2+ ions preferably forms a stable EDTA- Ca2+/Mg2+ complex with EDTA leaving the free EBT indicator in solution which is steel blue in colour in the presence of ammonia buffer (mixture of ammonium chloride and ammonium hydroxide, pH 10).

Why EDTA is more stable than EBT?

EDTA is insoluble in water at low pH because H4Y is predominant in that pH (less than 2). With increasing the pH, each hydrogen ion in the carboxyl groups of EDTA will start to dissociate. … As we need Y4- to react with the metal ions present in the titration solution, we use pH 10 buffer such as ammonium chloride.

What is an alternative indicator to EBT?

It is an azo dye.

Which buffer is used in EDTA method?

pH 10 buffer is used in EDTA titration because in EDTA Y4- is predominant, and we want Y4- to react with the metal ions that are present in the titration solution. This can be achieved by using a pH 10 buffer.

Why buffer is added in determination of hardness of water?

So, what do you do if you suspect you have hard water? … In order for this analysis to work well, the water sample must be kept at a basic pH. Since both EDTA and the indicator are themselves weak acids, a buffer solution , which is able to maintain a fairly constant pH even when acids and bases are added, is used.

Why is the end point of titration wine red to blue?

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.