In an iodometric titration, a starch solution is used as an indicator since it can absorb the I 2 that is released. This absorption will cause the solution to change its colour from deep blue to light yellow when titrated with standardised thiosulfate solution.
What is the principle of Iodometry?
The Basic Principle of iodometric titration is to determine the concentration of an oxidising agent in solution. iodometry involves indirect titration of iodine liberated by reaction with the analyte.In an iodometric titration, a starch solution is used as an indicator since it can absorb the I2 that is released.
What are the differences between Iodimetry and Iodometry?
Iodometry is the quantitative analysis of a solution of an oxidizing agent by adding an iodide that reacts to form iodine whereas iodimetry is a volumetric analysis involving either titration with a standardized solution of iodine.
What period is iodine in?
5
Fact box
| Group | 17 | Melting point |
|---|---|---|
| Period | 5 | Boiling point |
| Block | p | Density (g cm−3) |
| Atomic number | 53 | Relative atomic mass |
| State at 20°C | Solid | Key isotopes |
Why iodometric titrations are done in dark?
The reaction mixture should be kept in the dark before titration because light accelerates a side reaction in which iodide ions are oxidized to iodine by atmospheric oxygen.
Why iodometric titrations are done quickly?
In these cases the titration of the liberated iodine must be completed quickly in order to eliminate undue exposure to the atmosphere since an acid medium constitutes an optimum condition for atmospheric oxidation of the excess iodide ion.
How do you do iodometric titration?
Add to Erlenmeyer flask 50 mL of demineralized water, 10 mL of sulfuric acid solution, 10-15 mLs of potassium iodide solution, and two drops ammonium molybdate solution. Titrate with 0.1 N sodium thiosulfate to faint yellow or straw color. Swirl or stir gently during titration to minimize iodine loss.
Why KI is added in iodometric titration?
Excess KI is added to help solubilise the free iodine, which is quite insoluble in pure water under normal conditions.
Which indicator is used in Iodometry?
Potassium Iodide: Aqueous potassium iodide (KI) has a light orange-brown colour. It is used for testing the presence of oxidising agents; It is also used in iodometric solutions.
Why we use NaHCO3 for iodometric titration?
Sodium thiosulfate the usual titrant used for iodometric titrations. To keep the thiosulfate solution stable, NaHCO3 , which is a weak base helps to keep the solution slightly alkaline to slow down the decomposition of thiosulfate.
