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Why is it that during titration of iodine or triiodine with thiosulphate the starch indicator should not be added until near the end point?
Pralet
The Starch-Iodide complex is not very soluble in water, so the starch is added near the endpoint of an Iodine titration, when the Iodine concentration is low. This eliminates errors due to the fact that some Iodine may remain adsorbed on the complex and go undetected.
so if you add the starch indicator only right near the end point when the solution is a light yellow colour the starch shouldn't complex and go lumpy.
Wiki User
∙ 12y ago
Wiki User
∙ 13y agoToo early addition might block the iodine molecules in the internal structure of the alpha-starch helix.
First this doesn't give good and sharp color change from blue to colourless, secondly some iodine may not react at all giving a wrong outcome.
Just some drops of added titrant before end point, when the solution is turning from brown to yellow, the added starch indicator will give a full purple-blue iodine-starch-complex color (should not be black!: still too much I2).
Wiki User
∙ 12y agoBecause the blue complex formed with high concentrations of iodine is insoluble and does not re-dissolve as more thiosulfate is added.
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What is the reason of heating solution during redox titration?
This is far to be a rule for this titration.
Why is a small amount of indicator added during titration?
An indicator shows when we have added just enough of the second reagent to react with the first. If you mean why do we add only a small amount of indicator, it is to keep the answer accurate. Some of the reagent is used changing the indicator so the answer is always slightly bigger than perfection, and the more indicator you add, the larger the error.
During titration a student adds water to the beaker with the acid Will this affect the results?
No, at least if it doesn't contain something he's titrating. Too much can influence the sudden change at the end point, so no indicator will 'see' it.
What is the need for an ammonical buffer solution in the determination of hardness of water by edta titration?
during the complexometric titration using edta it is very necessary to maintain the ph of the solution near about 10 so we use ammonium chloride buffer if we will not use this buffer dring the titration ph of sol. will ho lower side
Describe why the indicator reaction is pH dependent?
An indicator reaction is always pH dependent because it involves hydrogen. During the reaction, hydrogen ions are either released or captured during the process.
Indicator used during the standardization of sodium thiosulphate?
Starch
What is the purpose for using phenolphthalein for an acid base titration?
It's the colour indicator you watch for during the titration.
Why is sulfuric acid added to the dilute bleach and iodide in the conical flask during titration of sodium hypochlorite with sodium thiosulphate?
to acidify the solution
Why is important that the indicator is present in the solution during the course of titration?
the reason why a indicator is important in some titration is to show a change in the solution. for example as a solution runs from acidic to basic the indicator may turn a different color. but this is the reason why it is important inmost experiments.
Why is it that 2 or 3 drops of the indicator is added during titration of acid and base?
To see where the equivalent point is
What happens during an acidic base titration in the presents of an indication?
The indicator will change color as the pH changes.
In HCl and NaOH titration which indicator is used?
Phenolphthalein indicates red for acids and blue for bases.
Why double indicator is used during the titration of water to find alkalinity of water sample?
A double indicator is used to find the alkalinity of the water sample to prevent errors.
What type of indicator is used during potassium permanganate titration?
Usually there is no indicator needed in potassium permanganate titrations as there will be an excess of manganate ions in the conical flask, turning the solution from colourless to pale pink.
What is an indicator blank?
During an experiment for chemistry, if an indicator will not work due to the lack of a reactant, the reactant can be added. You must then compensate for the added amount by creating a solution of the indicator and the the same amount of the reactant. The volume required in the blank titration must then be subtracted from the other results to obtain quality results. This is an indicator blank and how it is used.
What is the endpoint of a titration?
during a titration when a titrant completely furnished the sample then this is the end point of titration.
What is the reason of heating solution during redox titration?
This is far to be a rule for this titration.
