- Silver iodide
Chembox new
Name = Silver iodide
ImageFile = Silver-iodide-3D-balls.png
OtherNames = Silver(I) iodide
Name =
Section1 = Chembox Identifiers
CASNo = 7783-96-2
Section2 = Chembox Properties
Formula = AgI
MolarMass = 234.773 g/mol
Appearance = yellow, crystalline solid
Density = 5.675 g/cm3, solid
Solubility = 3x10-7g/100mL (20 °C)
MeltingPt = 552°C
BoilingPt = 1506°C
Section4 = Chembox Thermochemistry
DeltaHf = -62.4 kJ/mol at 1 atm
Section7 = Chembox Hazards
EUClass = not listed
NFPA-H = 2
NFPA-R = 0
NFPA-F = 0Silver iodide (AgI) is a
chemical compound used inphotography and as anantiseptic in medicine.Silver iodide is highly insoluble in water and has acrystalline structure similar to that of ice, allowing it to inducefreezing (heterogeneousnucleation ) incloud seeding for the purpose ofrainmaking .The crystalline structure adopted by silver iodide changes with temperature. The following phases are known: [cite journal | last=Binner | first=J. G. P. | coauthors=Dimitrakis, G.; Price, D. M.; Reading, M.; Vaidhyanathan, B. | title=Hysteresis in the β–α Phase Transition in Silver Iodide | journal=Journal of Thermal Analysis and Calorimetry | volume=84 | year=2006 | pages=409–412 | url=http://www.sump4.com/publications/paper047.pdf | format=
pdf | doi=10.1007/s10973-005-7154-1 ]
*Up to 420K (147 °C), AgI exists in the β-phase, which has a wurtzite structure. It is known as the mineraliodargyrite .
*Above 420K (147 °C), AgI undergoes a transition to the α-phase, which has a body-centered cubic structure and has the silver ions distributed randomly between 2-, 3-, and 4-coordinate sites.
*A metastable γ-phase also exists below 420K, which has a zinc blende structure.ilver iodide as a
fast ion conductor The transition between the β and α forms represents the melting of the silver (cation) sublattice. The
entropy of fusion (melting) for α-AgI is approximately half that forsodium chloride (a typical ionic solid). This can be rationalised by noting that the AgI crystalline lattice has essentially already partly melted in the transition between α and β forms. Adding the entropy of transition from α-AgI to β-AgI to the entropy of fusion gives a value that is much closer to the entropy of fusion for sodium chloride.References
In Media
*In the television series "The Batman", Poison Ivy used silver iodide to create rain so that she could populate Gotham City with her new breed of plants that assisted her in taking over the city.
*In the anime and manga
One Piece a green powder similar to silver iodide called Dance Powder was used to make rain when burnt and its use in the desertic land of Arabasta caused a war.External links
* [http://www.greatvistachemicals.com/pharmaceutical_intermediates/silver_iodide.html A commercial site (Vista Chemicals) regarding silver iodide]
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