iodometrically

Iodometrically refers to a method of chemical analysis that uses iodine to determine the concentration of a substance. This technique relies on the fact that iodine can participate in redox reactions. In many iodometric titrations, iodine is used as a titrant, meaning it is the solution of known concentration added to react with the analyte, the substance whose concentration is being determined. Alternatively, iodine can be liberated in situ and then titrated.

A common application of iodometry is in the determination of oxidizing agents. For example, an oxidizing agent will react with iodide ions to produce iodine. The amount of iodine produced is directly proportional to the amount of oxidizing agent present. This liberated iodine can then be titrated with a standard solution of sodium thiosulfate, using starch as an indicator. The endpoint is reached when the blue-black color of the starch-iodine complex disappears.

Iodometric methods are also used to quantify reducing agents, often indirectly. In such cases, a known excess of an oxidizing agent is first added to react with the analyte. This excess oxidizing agent is then reacted with iodide ions to produce iodine. The iodine liberated is subsequently titrated with thiosulfate. By knowing the amount of thiosulfate used, and accounting for any iodine produced by the initial oxidizing agent itself, the concentration of the original reducing agent can be calculated. The versatility and sensitivity of iodometric titrations make them a valuable tool in analytical chemistry.