Why phenolphthalein is not used in EDTA titration?
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).
Why is phenolphthalein not a good indicator for acids?
In the same way in the Titration of weak base versus strong acid there is a sudden change in the pH of 3.5 to 8.0,near the neutralisation point. So Phenolphthalein can’t be used since its pH range is 8.3 to 10.0.
What indicator is used in titration of EDTA?
In the case of EDTA titrations, the indicators are organic colorants that form coloured chelates with metal ions. The most commonly-used indicator is eriochrome black T. This is a triprotic acid.
Can phenolphthalein be used as an indicator?
Phenolphthalein is often used as an indicator in acid–base titrations. For this application, it turns colorless in acidic solutions and pink in basic solutions. It belongs to the class of dyes known as phthalein dyes.
Why phenolphthalein is not used in complexometric titration?
Why is phenolphthalein not used as an indicator in EDTA titration? – Quora. 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.
Why is phenolphthalein and methyl orange not used in complexometric titration?
The titration shows the end point lies between pH 8 and 10. This is due to the hydrolysis of sodium acetate formed. Hence phenolphthalein is a suitable indicator as its pH range is 8-9.8. However, methyl orange is not suitable as its pH range is 3.1 to 4.5.
Why is phenolphthalein used as an indicator in titration?
Phenolphthalein is used as an indicator in acid-base titration as it indicates the change in pH by changing its colour [actually, going from colourless (in acidic solution) to pink colour(in basic solution)].
Which indicator is used in titration?
Phenolphthalein
Phenolphthalein, a commonly used indicator in acid and base titration.
What is the role of indicator in complexometric titration?
In analytical chemistry, complexometric indicators are used in complexometric titration to indicate the exact moment when all the metal ions in the solution are sequestered by a chelating agent (most usually EDTA). When such solution loses color during titration, a drop or two of fresh indicator may have to be added.
Why phenolphthalein is used as indicator for the reaction?
A strong acid- strong base titration is performed using a phenolphthalein indicator. Phenolphtalein is chosen because it changes color in a pH range between 8.3 – 10. It will appear pink in basic solutions and clear in acidic solutions.
In which titration experiment phenolphthalein is not used as indicator?
In the titration of Na2CO3 with HCl using methyl orange indicator, the volume of the acid required at the equivalence point is twice that of the acid required using phenolphthalein as indicator.
What is the difference between EDTA titration and phenolphthalein titration?
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).
Why is EDTA insoluble in water at low pH?
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. Above pH 10, Y4- is predominant. As we need Y4- to react with the metal ions present in the titration solution, we use pH 10 buffer such as ammonium chloride.
Why phenolphthalein and methyl orange not used as indicator in dictator of calcium?
Why is phenolphthalein and methyl orange not used as indicator in dictator of calcium Both MO and phenolphthalein are indicators of pH of a solution; i.e., both are acid/base indicators. The calcium/EDTA titration is not an acid/base titration. The Ca/EDTA titration is a complexometric one.
What is a pH sensitive indicator in acid base titration?
In an acid base titration a pH sensitive indicator is used. At a certain pH range the proton is attached or released depending upon whether the range is approached from higher or lower pH. Since the protonized form of the indicator differs markedly in color from the unprotonized form, a color change accompanies the reaction.