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.
This is far to be a rule for this 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.
Adding water to the beaker with the acid during titration will dilute the acid solution, potentially altering the concentration and thus affecting the results. It is important to maintain the initial concentration of the acid solution throughout the titration process for accurate results.
In iodometric titrations sodium thiosulfate is the titrant whereas the KI will reduce the analyte; eg: Cu2+ to Cu+. The I2 produced is then titrated by the sodium thiosulphate. Cu2+ + I- --> CuI + I3- I3- + 2 S2O32- ¾® 3 I- + S4O62- To answer your question: KI (reducing agent) is added to generate the iodine by the reduction of the analyte (Cu2+) The formed iodine is then back-titrated with thiosulfate (titrant) to determine the amount of analyte originally present. As you can see the KI and sodium thiosulfate serve two different purposes. KI improves solubility of Iodine
Redox titration involves a reaction between an oxidizing agent and a reducing agent. During the titration, electrons are transferred from the reducing agent to the oxidizing agent, resulting in a change in oxidation states. The equivalence point is reached when the moles of the oxidizing agent are stoichiometrically equivalent to the moles of the reducing agent.
Starch
Phenolphthalein is the indicator that turns pink in basic solutions during titration reactions.
A thiosulfate titration is mostly carried out to determine the amount of iodine present in the solution. In these reactions, thiosulfate ion acts as the reducing agent. This types titrations are often called as 'iodometric titrations'.
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.
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 used in potentiometric titrations is typically a pH electrode. By measuring changes in pH during the titration process, the endpoint of the titration can be determined accurately. The pH electrode provides a continuous measurement of the solution's pH, allowing for a precise determination of the equivalence point.
Phenolphthalein is used as an indicator during the titration of tartaric acid because the pH at which phenolphthalein changes color (around pH 8.2-10) is close to the equivalence point of the titration of tartaric acid with a strong base like NaOH. This makes it a suitable indicator for detecting the endpoint of the titration when the acid has been completely neutralized by the base.
Platinum electrode is used as the indicator electrode in potentiometry titration to measure the potential difference between the indicator electrode and the reference electrode. It provides a stable and reproducible potential during the titration process, allowing for accurate determination of the equivalence point. Platinum electrodes are inert and do not participate in the redox reactions happening during the titration, making them suitable for a wide range of titrations.
Indicators are weak acid. Too much will alter the titre
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.
During an acid-base titration, an indicator is added to the solution to determine the endpoint, which is when the moles of acid are equal to the moles of base. The indicator changes color at the endpoint, indicating the completion of the reaction. This color change helps in identifying the point of neutralization and determining the concentration of the unknown solution.
An external indicator in titration is a substance that is added in small amounts to the analyte solution during titration to signal the endpoint of the reaction. It changes color at or near the equivalence point, making it easier for the observer to detect when the reaction is complete. Common examples of external indicators include phenolphthalein and methyl orange.