Potassium compounds: potassium iodide
The potassium in potassium iodide formally is in the oxidation state 1.
- Formula as often written: KI
- Hill system formula: I1K1
- CAS registry number: [7681-11-0]
- Formula weight: 166.003
- Class: iodide
- potassium iodide
- potassium(I) iodide
- Colour: white
- Appearance: crystalline solid
- Melting point: 681°C
- Boiling point: 1323°C
- Density: 3120 kg m-3
Element percentages for the elements in potassium iodide
One way to make potassium iodide is to react the hydroxide with hydroiodic acid. The resulting salt can then be purified by recrystallization.
KOH(aq) + HI(aq) → KI(aq) + H2O(l)
While not a normal route of preparation because of the expense, potassium metal reacts vigorously with all the halogens to form potassium halides. So, it burns with iodine, I2, to form potassium(I) iodide, KI.
2K(s) + I2(s) → 2KI(s)
Solid state structure
- Geometry of potassium: 6 coordinate: octahedral
- Prototypical structure: NaCl (rock salt)
What follows is the calculated isotope pattern for the KI unit with the most intense ion set to 100%.
166 100.0 __________________________________________________
168 7.2 ____
The data on these compounds pages are assembled and adapted from the primary literature and several other sources including the following.
- R.T. Sanderson in Chemical Periodicity, Reinhold, New York, USA, 1960.
- N.N. Greenwood and A. Earnshaw in Chemistry of the Elements, 2nd edition, Butterworth, UK, 1997.
- F.A. Cotton, G. Wilkinson, C.A. Murillo, and M. Bochmann, in Advanced Inorganic Chemistry, John Wiley & Sons, 1999.
- A.F. Trotman-Dickenson, (ed.) in Comprehensive Inorganic Chemistry, Pergamon, Oxford, UK, 1973.
- R.W.G. Wyckoff, in Crystal Structures, volume 1, Interscience, John Wiley & Sons, 1963.
- A.R.West in Basic solid state chemistry Chemistry, John Wiley & Sons, 1999.
- A.F. Wells in Structural inorganic chemistry, 4th edition, Oxford, UK, 1975.
- J.D.H. Donnay, (ed.) in Crystal data determinative tables, ACA monograph number 5, American Crystallographic Association, USA, 1963.
- D.R. Lide, (ed.) in Chemical Rubber Company handbook of chemistry and physics, CRC Press, Boca Raton, Florida, USA, 77th edition, 1996.
- J.W. Mellor in A comprehensive treatise on inorganic and theoretical chemistry, volumes 1-16, Longmans, London, UK, 1922-1937.
- J.E. Macintyre (ed.) in Dictionary of inorganic compounds, volumes 1-3, Chapman & Hall, London, UK, 1992.