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Potassium iodide | |
---|---|
Names: | potassium iodide potassium jodide |
Formula: | KI |
Molar mass: | 165.998 g/mol |
Density: | 3.123 g/cm3 |
Crystal system: | cubic a=7.06 Å, b=7.06 Å, c=7.06 Åα=90°, β=90°, γ=90° |
Shapes: |
|
Color: | colorless |
Melting point: | 681 °C954.15 K <br />1,257.8 °F <br />1,717.47 °R <br /> |
Boiling point: | 1330 °C1,603.15 K <br />2,426 °F <br />2,885.67 °R <br /> |
Refractive index: | 1.667 |
Magnetic properties: | diamagnetic |
Radiation properties: | slightly radioactive |
Stability: | slightly hygroscopic |
Hardness: | strong |
Toxicity: | non-toxic LD50=2779mg/kg |
Description
Inorganic compound, salt of alkaline metal potassium and inorganic hydroiodic acid. Doesn't form water hydrates.
Precursors
Reaction between iodine, potassium hydroxide and hydrogen peroxide
Chemical equation:
100.00
g of potassium iodide а 33.80
g of hydroxide, 341.51
g of 3%
peroxide and 76.45
g of iodine is required.Add to the flask with hydroxide solution hydrogen peroxide and then add small parts of iodine with stirring until oxide emission will stop. For purifying compound from hydroxide add large amount of cold ethanol, acetone or toluene to solution, salt will settle to the bottom in the form of fine crystals or powder. Filter precipitate and wash it with small amount of the same solvent, then filter the solution and use it for crystal growing.
Reaction between potassium hydroxide or carbonate фтв hydroiodic acid
Chemical equation:
100.00
g of potassium iodide а 33.80
g of hydroxide or 41.63
g of carbonate and 135.18
g of 57%
hydrobromic acid is required.Add acid to the flask, then add small parts of potassium compound with stirring until heating will stop (attention, the solution may boil!) or, if you use carbonate, until carbon dioxide emission will stop.
The problem is that hydroiodic acid is rarely occurs, so reaction is rarely used.
Influence of temperature
Dissolving is endothermic, solution cools much, so use hot water or using heat.
Rapid cooling causes prismatic crystals growth.
Influence of impurities
Excess of iodine causes reddening of solution, excess of potassium hydroxide causes slowing down crystal growth or finally stops it.
Notes
Reacts with humid air with forming iodine at the crystal surface, so crystals becomes more dark-colored.
Too big solubility in water is intervenes growing process, so using organic solvents should be preferred.
Storage conditions
Keep in its original form or under several layers of varnish at average humidity and room temperature. Do not keep crystals near heaters.
Solubility
Temperature | g/100,00 g water | g/100,00 g ethanol 40% | g/100,00 g ethanol | g/100,00 g methanol | g/100,00 g acetone | g/100,00 g diethyl ether | g/100,00 g glycerol | g/100,00 g DMSO | g/100,00 g pyridine | g/100,00 g furfural | g/100,00 g ethylene glycol | g/100,00 g formic acid 95% | g/100,00 g propanol | g/100,00 g isobutanol | g/100,00 g 1-butanol | g/100,00 g 2-butanol | g/100,00 g ammonia | g/100,00 g ethylenediamine | g/100,00 g hydroxylamine | g/100,00 g acetamide | g/100,00 g dimethylformamide | g/100,00 g nitromethane | g/100,00 g acetonitrile | g/100,00 g benzonitrile | g/100,00 g propionitrile | g/100,00 g amyl alcohol | g/100,00 g benzaldehyde | g/100,00 g salicylic aldehyde |
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0°C273.15 K <br />32 °F <br />491.67 °R <br /> | 127.3 | 1.5 | 2.31 | 184.2 | 0.316 | 2.31 | 0.0429 | 1.105 | ||||||||||||||||||||
10°C283.15 K <br />50 °F <br />509.67 °R <br /> | 135.8 | ~1.63 | 13.6 | |||||||||||||||||||||||||
15°C288.15 K <br />59 °F <br />518.67 °R <br /> | ~1.69 | |||||||||||||||||||||||||||
20°C293.15 K <br />68 °F <br />527.67 °R <br /> | 144.5 | 1.75 | 15.1 | 50 | 16 | 0.5 | 50 | 38.2 | 110 | |||||||||||||||||||
25°C298.15 K <br />77 °F <br />536.67 °R <br /> | 148.6 | 4.82 | 1.88 | 2.04 | 39.66 | 5.2 | 36.05 | 0.43 | 0.0955 | 0.201 | 0.0582 | 74.9 | 25 | 0.307 | 0.0506 | 0.0404 | 0.098 | 0.329 | 0.485 | |||||||||
30°C303.15 K <br />86 °F <br />545.67 °R <br /> | 152.5 | 16.3 | ||||||||||||||||||||||||||
40°C313.15 K <br />104 °F <br />563.67 °R <br /> | 159.7 | 18.1 | ||||||||||||||||||||||||||
50°C323.15 K <br />122 °F <br />581.67 °R <br /> | 18.9 | |||||||||||||||||||||||||||
60°C333.15 K <br />140 °F <br />599.67 °R <br /> | 175.5 | |||||||||||||||||||||||||||
70°C343.15 K <br />158 °F <br />617.67 °R <br /> | 21.65 | |||||||||||||||||||||||||||
80°C353.15 K <br />176 °F <br />635.67 °R <br /> | 190.7 | |||||||||||||||||||||||||||
90°C363.15 K <br />194 °F <br />653.67 °R <br /> | 198 | |||||||||||||||||||||||||||
100°C373.15 K <br />212 °F <br />671.67 °R <br /> | 206.7 | 25 |
Gallery
Sources
Iodides | |
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Salts |
Germanium iodide (GeI4) • Cadmium iodide (CdI2) • Lead(II) iodide (PbI2) • Potassium iodide (KI) • Sodium iodide (NaI) • Tin(II) iodide (SnI2) |
Complexes |
Potassium tetraiodobismuthate (К[BiI4]) • Potassium tetraiodomercurate(II) (K2[HgI4]) |