Which indicator is used in the determination of potassium iodate?
Potassium Iodate can also be used as a basimetric standard for standardization of strong acids. A slight excess of both Potassium Iodate and Potassium Iodide is added, and the Iodine generated (see the first equation above) is then titrated with standard Sodium Thiosulfate using Starch indicator.
Which titrant is used in determination of potassium iodate and iodine?
Determination of iodine can be done by iodometric titration, whereas iodide and iodate can be analyzed by ion chromatography.
Why is potassium iodate a primary standard?
Potassium Iodate is an oxidizing agent and a good primary standard with the one drawback of having a relatively low equivalent weight. It is used primarily as a stable source of Iodine, which is liberated in the presence of Iodide ion and acid, in the titration of Thiosulfate and Sulfite solutions. Full story…
Why do we add KI in iodometric titration?
Potassium iodide must be added in excess to keep iodine dissolved. Once all the ascorbic acid has been consumed, any excess iodine will remain in solution. Since aqueous iodine solutions are brown in colour, iodine can act as its own indicator.
What is role of KI in iodine number titration?
The iodine monochloride reacts with the unsaturated part of the oil or fat, the double bonds, adding iodine to the molecule. Potassium iodide is then added which liberates any unreacted iodine. This is determined by titration with sodium thiosulphate.
Why excess KI is used in standardization process?
Excess KI is added to help solubilise the free iodine, which is quite insoluble in pure water under normal conditions. The preferred water for this method should be boiled distilled water, which requires provision of a distillation unit.
Why is HCl added for the titration of vitamin C?
Hydrochloric acid (HCl) is added during titration of vitamin C (C6H8O6) because the reaction should be carried out in an acidic medium.
Why only freshly prepared starch solution is used in iodometric titration?
The starch indicator solution must be freshly prepared since it will decompose and its sensitivity is decreased. However, a properly prepared solution will keep for a period of a few weeks. A preservative such as a small amount of mercuric ions may be added to inhibit the decomposition.
Why is HCl not used as a primary standard?
Hydrochloric acid, HCl, and sulfuric acid, H2SO4, are NOT suitable for use as a primary standard because although they are both commercially available as concentrated solutions that are easily diluted, the concentration of the “concentrated” solution is NOT accurately known.
Is potassium hydrogen iodate a primary standard?
Potassium hydrogen iodate, primary standard, ACS, 99.95-100.05%, Thermo Scientific™
Why excess of KI is used in iodometric titration?
Why HCl is used in iodometric titration?
Firstly, iodometric titration is a redox process, so acids which can oxidize or be oxidized should not be used. Nitric acid is an oxidizer, hydrochloric acid can be oxidized to chlorine, so these should not be used. Both sulfuric acid and acetic acid are free of these problems.
Why do we use excess of KI in iodometric titration?
Excess KI is added to help solubilise the free iodine, which is quite insoluble in pure water under normal conditions.