Difference Between Iodometry and Iodimetry

When an analyte that is an oxidizing agent is added to excess iodide to produce iodine, and the iodine produced is determined by titration with sodium thiosulfate, the method is called iodometry.
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Iodometry.

1. What do you mean by Iodimetry?
2. What is the principle of iodometric titration?
3. Why is KI used in iodometric titration?
4. Why starch is used as indicator?
5. Why sodium thiosulphate is used in titration?
6. Why is starch solution added only at the end of titration?
7. Why is starch not added at the beginning of titration?
8. What is the purpose for including starch in the sodium thiosulfate solution?
9. What color is starch indicator?
10. Why is iodine kept in the dark?
11. What kind of indicator is starch?

What do you mean by Iodimetry?

Volumetric analysis involving either titration with a standardized solution of iodine, or the release by a substance under examination of iodine in soluble form, so that its concentration can be determined by titration, using starch as an indicator.

What is the principle of iodometric titration?

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.

Why is KI used in iodometric titration?

Liberation of free iodine from salt: The addition of H2S4O liber- ates free iodine from the iodate in the salt sample. Excess KI is added to help solubilise the free iodine, which is quite insoluble in pure water under normal conditions.

Why starch is used as indicator?

Starch is a viable indicator in the titration process because it turns deep dark blue when iodine is present in a solution. When starch is heated in water, decomposition occurs and beta-amylose is produced. Beta-amylose combines with iodine, resulting in a dark blue color change.

Why sodium thiosulphate is used in titration?

In an iodometric titration, a starch solution is used as an indicator since it can absorb the I2 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. This indicates the end point of the titration.

Why is starch solution added only at the end of titration?

In iodometry the starch is added only after the color due to triiodide has begun to fade, i.e., near the endpoint, because starch can be destroyed in the presence of excess triiodide. iodide in acid solution to yield triiodide, which is subsequently titrated with the standardized thiosulfate solution.

Why is starch not added at the beginning of titration?

Starch is now used as an indicator for the presence of iodine. ... As to why it is added near the end of the titration rather than at the beginning is because the starch-iodine complex at high I2 concentrations is relatively stable. The release of I2 from the starch-iodine complex is slow at high I2 concentrations.

What is the purpose for including starch in the sodium thiosulfate solution?

It stabilizes the thiosulfate to keep it from oxidizing when exposed to air. It acts as a catalyst to increase the reaction rate so the experiments can be completed in the lab period.

What color is starch indicator?

Using iodine to test for the presence of starch is a common experiment. A solution of iodine (I₂) and potassium iodide (KI) in water has a light orange-brown color. If it is added to a sample that contains starch, such as the bread pictured above, the color changes to a deep blue.

Why is iodine kept in the dark?

In presence of light Iodine solution undergoes a photo-decomposition reaction so it must be stored in a dark bottle , generally in amber bottle to minimize the amount of light that the solution is exposed to.

What kind of indicator is starch?

Starch as an indicator

Starch is often used in chemistry as an indicator for redox titrations where triiodide is present. Starch forms a very dark blue-black complex with triiodide. However, the complex is not formed if only iodine or only iodide (I⁻) is present.