Potassium+Iodide

**Potassium iodide** is an [|inorganic compound] with the [|chemical formula] [|K] [|I]. This white salt is the most commercially significant iodide compound, with approximately 37,000 tons produced in 1985. It is less [|hygroscopic] (absorbs water less readily) than [|sodium iodide], making it easier to work with. Aged and impure samples are yellow because of aerial [|oxidation] of the [|iodide] to elemental [|iodine]. [|[1]] 4 KI + 2 CO2 + O2 → 2 K2CO3 + 2 I2 Potassium iodide is medicinally supplied in 130 [|mg] tablets for emergency purposes. [|[2]] Potassium iodide may also be administered as a "saturated solution of potassium iodide" (**SSKI**) which in the [|U.S.P.] generic formulation contains 1000 mg of KI per mL of solution. This represents 333 mg KI and about 250 mg iodide (I -) in a typical adult dose of 5 drops, assumed to be ⅓ mL. [|[3]] Because SSKI is a viscous liquid, it is normally assumed to contain 15 drops/milliliter, not 20 drops/milliliter as is often assumed for water. [|[4]] Thus, each drop of U.S.P. SSKI is assumed to contain about 50 mg iodine as iodide, I -. Thus, two (2) drops of U.S.P. SSKI solution is equivalent to one 130 mg KI tablet (100 mg iodide). SSKI can also be prepared by truly saturating water with KI. This preparation can be made without a measuring scale. Since the solubility of KI in water at room temperature is about 1.40 to 1.48 grams per mL pure water, and the resulting solution has a density of about 1.72 g/mL, this process also results in a final [|concentration] of KI of about 1000 mg KI per mL of saturated KI solution, and also contains essentially the same concentration of iodide per drop as does the U.S.P. formulation. SSKI is extremely bitter, and if possible it is administered in a sugar cube or small ball of bread. Neither SSKI or KI tablets are used as nutritional supplements, since the nutritional requirement for iodine is only 150 micrograms or 0.15 mg of iodide per day. Thus, a drop of SSKI provides 50/0.15 = 333 times the daily iodine requirement, and a standard KI tablet provides twice this much.  [|Kelp] is a natural KI source. [|[5]] The iodide content can range from 89 [|µg] /g to 8165 µg/g in Asian varieties, making prepared foods content difficult to estimate. [|[6]] Eating 3-5 grams of most dried, unrinsed seaweeds will provide the 100-150 micrograms iodide recommended daily allowance for nutritional purposes. Potassium iodide is [|ionic], K+I−. It crystallises in the [|sodium chloride] structure. It is produced industrially by treating KOH with iodine. [|[1]]

 Inorganic chemistry
Since the [|iodide] ion is a mild [|reducing agent], I − is easily oxidised to [|I2] by powerful [|oxidising agents] such as [|chlorine] : 2 KI( [|aq] ) + Cl2(aq) → 2 [|KCl] + I2(aq) This reaction is employed in the isolation of iodine from natural sources. Air will oxidize iodide, as evidenced by the observation of a purple extract when aged samples of KI are rinsed with [|dichloromethane]. As formed under acidic conditions, [|hydroiodic acid] (HI) is a stronger reducing agent. [|[8]] [|[9]] [|[10]] Like other iodide salts, KI forms [|I3−] when combined with elemental [|iodine]. KI(aq) + [|I2] ( [|s] ) → KI3(aq) Unlike I2, I3− salts can be highly water-soluble. Through this reaction [|iodine] is used in [|redox] [|titrations]. Aqueous KI3, " [|Lugol's solution] ," are used as disinfectants and as etchants for gold surfaces. Potassium iodide is the precursor to [|silver(I) iodide], which is used for high speed [|photographic film] : KI(aq) + [|AgNO3] (aq) → AgI(s) + [|KNO3] (aq)

<span style="background-color: #ffffff; color: #000000; font-family: sans-serif; font-size: 17px; text-align: start;"> Organic chemistry
<span style="background-color: #ffffff; color: #000000; font-family: sans-serif; font-size: 13px; text-align: start;">KI serves as a source of iodide in [|organic synthesis]. A useful application is in the preparation of aryl iodides from [|arenediazonium salts]. [|[11]] [|[12]] For example: <span style="background-color: #ffffff; color: #000000; font-family: sans-serif; font-size: 13px; text-align: start;"> <span style="background-color: #ffffff; color: #000000; font-family: sans-serif; font-size: 13px; text-align: start;">KI, acting as a source of iodide, may also act as a [|nucleophilic catalyst] for the alkylation of alkyl [|chlorides], [|bromides] , or [|mesylates].