eriochrome black T is an indicator for EDTA titration
In an EDTA titration using Eriochrome Black T indicator, the pink color indicates the presence of free metal ions, such as calcium or magnesium, which form complexes with the indicator. As EDTA is added, it binds to these metal ions more strongly than the indicator does, causing the indicator to release the metal and change color. At the endpoint, when all the metal ions have reacted with EDTA, the indicator turns blue due to its transition to a form that is free of metal ions, indicating that the titration is complete.
The Eriochrome Black T (EBT) indicator changes color when it forms a complex with calcium and magnesium ions, which are responsible for water hardness. This color change signals the endpoint of the titration when all the calcium and magnesium ions are complexed with EDTA. Therefore, EBT is used to detect the endpoint of the titration and determine the water hardness.
Starch indicator is added during the standardization of hypo solution (sodium thiosulfate) to visually signal the endpoint of the titration. When iodine is present, it forms a blue complex with starch, indicating excess iodine. As sodium thiosulfate is added and reacts with iodine, the blue color disappears, signaling that all the iodine has reacted. This color change provides a clear and distinct endpoint for accurate titration results.
That would probably be referring to iodine.
When starch is no longer present, the indicator iodine turns from blue-black to a yellow or brown color. This change occurs because iodine forms a blue-black complex with starch, and in the absence of starch, the iodine remains in its free state, resulting in the lighter color.
Another example of an indicator used in a titration with EDTA is Eriochrome Black T. This indicator changes color from red to blue when it forms a complex with metal ions, allowing for the detection of the end point in the titration.
Starch is added at the end of titration as an indicator to signal the endpoint of the reaction. It forms a complex with the iodine produced during the titration, resulting in a color change from clear to blue-black, indicating that the titration is complete.
The indicator commonly used in EDTA titrations is Eriochrome Black T. It changes color from wine-red to blue when transitioning from calcium ions to magnesium ions, helping to detect the endpoint of the titration accurately.
Starch forms a blue-black complex with iodine, making it easy to see when the iodine has been fully neutralized in the titration. The color change is very distinct, allowing for accurate endpoint determination in the titration process.
Starch solution is used as an indicator in redox titrations to detect the endpoint of the titration. It forms a complex with triiodide ions to produce a blue-black color when excess iodine is present, indicating that the reaction has reached completion. This helps in determining the equivalence point of the titration.
Starch indicator should not be added at the beginning of an iodometry titration because iodine can form a complex with the starch, resulting in a blue-black color that can obscure the endpoint. It is best to add the starch indicator near the endpoint, when the iodine is almost completely reacted, to help visualize the color change.
Starch is used as an indicator in iodometric titration because it forms a blue color complex with iodine. This helps in visually detecting the endpoint of the titration, which is when all the iodine has been reacted with the analyte. The appearance of the blue color indicates that the reaction is complete.
Starch is added towards the end of titration as an indicator to help visualize the endpoint. When the starch is added, the solution will turn blue-black in the presence of excess iodine, indicating that the reaction is complete. This color change helps in accurately determining the endpoint of the titration.
The blue precipitate may indicate the presence of excess indicator in the solution. In redox titrations, the indicator changes color when the reaction reaches its endpoint. If too much indicator is added, it can form a colored precipitate due to its reaction with the titrant, which can obscure the endpoint of the titration. It is important to carefully control the amount of indicator to avoid this issue.
The indicator added to the sample is Eriochrome Black T. Initially, the indicator will form a complex with the cations. When complexed it is red in color. As the EDTA is added dropwise to the sample, it replaces the Erio T and forms more stable complexes with calcium and magnesium. When the indicator is released by the metal ions, it has a distinct blue color. Therefore, the endpoint of the titration is marked by the color change form red to blue
Phenolphthalein is an acid base indicator - it does not show the end-point in a thiosulfate type titration. Starch gives a very sharp end-point from a blue-black to colorless end-point when titrating iodine with thiosulfate. Phenolphthalein would just not detect this change.
Phenolphthalein is commonly used as an indicator in the titration of hydrochloric acid (HCl) with sodium hydroxide (NaOH). Phenolphthalein changes color from colorless to pink at the endpoint of the titration when all the acid has been neutralized by the base.