Potassium iodide
Potassium iodide is a chemical compound. Its chemical formula is KI. It has potassium and iodide ions in it.
Properties
It is a colorless crystalline solid. It is a weak reducing agent. It reacts with chlorine to make iodine and potassium chloride. It turns yellow when in air. This is because it reacts with oxygen and carbon dioxide to make iodine and potassium carbonate. It reacts with iodine to make the triiodide ion. That is why a solution of potassium iodide dissolves iodine.
Preparation
It is made by reacting iodine or hydriodic acid with potassium hydroxide.
Uses
It is used to supply iodine in the form of vitamin tablets or pills. It can be added to table salt to prevent a deficiency of iodine. It is also used to make silver iodide. It can be used to add iodine to organic compounds. It is used to prevent thyroid cancer by filling up the thyroid with normal iodine. After a nuclear explosion there normally is radioactive iodine in the air. The radioactive iodine collects in the thyroid and causes cancer. When the person takes potassium iodide it fills up the thyroid with iodine so no radioactive iodine can come in.
Potassium Iodide Media
Pheochromocytoma seen like a dark sphere in center of the body. Image is by MIBG scintigraphy with radiation from radioiodine in the MIBG. Note unwanted uptake of radioiodine from the pharmaceutical by the thyroid gland in the neck, in both images (front and back) of the same patient. Radioactivity is also seen in the bladder.
Sandmeyer reaction with potassium iodide
Distribution areas for iodine pills in the Netherlands (2017).
