IODOMETRY Key words: Iodimetry, Andrew's condition

Theory:
Iodometry refers to the titration of iodine liberated in chemical reaction (eq 1& 2). Titration with a standard solution of iodine is called an iodimetric titration (eq 3)

In this experiment you will be using KIO3. It is a very strong oxidizing agent and its oxidizing power depends on the conditions under which it is used.
In moderately acidic solution (0.1 -2.0M HCl) with reducing agents such as iodide ions reaction stops when the iodate is reduced to iodine (eq 4). With more powerful reductants like Ti(III) the iodate is reduced to iodide. (eq 5)

In most strongly acidic medium (3-6M HCl) reduction occurs to iodine monochloride. This is the most widely used condition and is known as Andrew’s conditions.

In the experiments given below you will be using strong HCl acid medium and the reaction proceeds through several steps.