Is iodine or iodine ion reacting with starch to turn blue?

Starch turns blue when it meets iodine, and iodine is iodine.

Element iodine is a purple-black crystal, which is easy to sublimate and condense after sublimation. Toxic and corrosive. Iodine turns blue-purple when it meets starch. Mainly used in the manufacture of drugs, dyes, iodine, test paper and iodine compounds.

Iodine is extremely important to the life of animals and plants. Iodide and iodate in seawater enter the metabolism of most marine organisms. In advanced mammals, iodine is concentrated in the thyroid gland in the form of iodinated amino acids, and iodine deficiency can lead to goiter. About two thirds of iodine and its compounds are used to prepare preservatives, disinfectants and drugs, such as tincture of iodine and iodoform chloroform. Sodium iodate as a food additive is not enough to supplement iodine intake. Radioisotope iodine-13 1 is used in radiotherapy and radioactive tracer technology. Iodine can also be used to make dyes and photographic films.

Silver iodide (AgI) is not only used as a sensitizer for photographic negatives, but also as a seed to form clouds during artificial rainfall. Alcohol solution of iodine and potassium iodide is a commonly used disinfectant. Iodoform (CHI3) is used as a preservative.

Iodine tincture, compound iodine solution, iodine throat tablets, iodine glycerin and other iodine preparations are widely used in medical treatment. Iodine tincture is a common disinfectant in the family.

Reaction of iodine with water;

(1) Type of reaction between halogen and water: self-oxidation-reduction reaction will occur in water.

(2) Reaction between iodine and water: Iodine has the smallest solubility in water, only slightly soluble in water, and its solubility is 0.029g/ 100g water. I2 can't react with water like F2. When oxygen is introduced into hydrogen iodide solution, iodine will precipitate;

4HI + O2 → 2I2 + 2H2O

Under alkaline conditions, I2 can undergo its own redox reaction to generate iodate and iodine ion.

3I2 + 6OH- → 5I- + IO3-+ 3H2O

This is because there is no iodate IO- in the solution. At any temperature, IO- will rapidly undergo its own redox reaction to generate I- and IO3-.

References:

Baidu encyclopedia iodine