Question

What happens when iodine reacts with hypo solution?

Answer 1

We have to remember that the hypo is the word given to sodium thiosulfate. The name is given from its original name that is hyposulphite of soda. It is a colorless pentahydrate salt. Iodine is a covalent compound. We need to know that reaction has various applications in practical chemistry and is helpful in the laboratory.

Complete answer:
We have to remember that the hypo solution that has the chemical formula $N{a_2}{S_2}{O_3}$ reacts with iodine. The reaction involved is a redox reaction. The hypo solution reduces the iodine preset into iodide. In hypo solution the sulphur present is in $+ 2$ oxidation state and gets oxidised to $+ 2.5$ state.
We must have to know that the sodium thiosulfate gets oxidised and forms sodium tetrathionate. The hypo gets oxidised itself and reduces the iodine. Since oxidation and reduction both occur simultaneously the reaction is termed as redox reaction. We must remember that the reaction has various applications and can be used in iodometric titration and in determination of rate of constant for various reactions.
The reaction is also used in iodometric titration. In the reaction the iodine that is added as potassium iodide gets oxidized to iodine and is liberated. This liberated iodine is then titrated against hypo solution. This reaction is used for determining the strength of solution.

Note:
We have to remember that the reaction is a redox reaction where oxidation and reduction occur simultaneously. The reaction must be a balanced chemical equation since the law of conservation of mass must be followed.