Question

The principal products obtained on heating iodine with concentrated caustic soda solution is:
A.$NaIO + NaI$
B.$NaIO + NaIO$
C.$NaI{O_3} + NaI + {H_2}O$
D. $NaI{O_4} + NaI$

Answer 1

On adding iodine to caustic soda (alkali) hypoiodite is formed and a peculiar smell is of iodoform and pale yellow colour .

Complete step by step answer:
Caustic soda is an alkali. On adding iodine to caustic soda iodoform is formed which has a peculiar smell. The solution becomes pale yellow in colour due to formation of iodoform.
The reaction which takes place when iodine reacts with caustic soda is as follows:
$6NaOH + 3{I_2} \to NaI{O_3} + 5NaI + 3{H_2}O$
The NaOH , sodium hydroxide , used in the above reaction should be cold and dilute. The reaction does not take place in hot and concentrated NaOH
Option ( C ) is correct.

Additional information: caustic soda is an alkali. It is an inorganic compound . It is also called sodium hydroxide ( NaOH ). It is also known as lye. It is white ionic solid. When caustic soda is dissolved in water $N{a^ + }$ and $O{H^ - }$ ions are produced. Caustic soda has various industrial applications. It is used in the manufacture of pulp and paper, alumina and petroleum. Besides it is a main compound of soap and detergent. Other applications include water treatment, food textile, metal processing, mining, glass making etc. it is also widely used in laboratories for experiment. Caustic soda is harmful. It can cause burns and permanent damage to the tissue which comes in direct contact. Caustic soda and baking soda look similar but they are two different chemical compounds. Caustic soda is sodium hydroxide whereas baking soda is sodium bicarbonate. Caustic soda is used in soaps and detergents whereas baking soda is used in cooking.

Note:
The sodium hydroxide ( NaOH ) used in the reaction should be cold and dilute. Reaction will not take place if NaOH is hot and concentrated.