Jodometria

Jodometria is a common analytical method used in chemistry to determine the concentration of a substance by measuring the amount of iodine it consumes or produces. This technique relies on the redox properties of iodine and iodide ions. Typically, jodometria involves a titration where a solution containing the analyte is reacted with a standardized solution of iodine or a substance that produces iodine in situ.

There are two main types of jodometria: direct and indirect titration. In direct jodometria, the analyte directly reacts with iodine. For example, reducing agents like sulfur dioxide or thiosulfate can be titrated with a standard iodine solution. The endpoint is usually indicated by a change in the color of iodine, which is often intensified by the addition of starch indicator, forming a deep blue complex.

Indirect jodometria, also known as iodometric titration, involves oxidizing an iodide ion to iodine, which is then titrated with a standard thiosulfate solution. This is commonly used for determining oxidizing agents, such as copper(II) ions or hypochlorites. The liberated iodine is then titrated with sodium thiosulfate, with starch serving as the indicator. The disappearance of the blue color signifies the endpoint. Jodometria is a versatile and widely applied technique in various fields, including water quality analysis, food chemistry, and pharmaceutical analysis.