Wikipedia:WikiProject Chemicals/Chembox validation/VerifiedDataSandbox and Silver iodide: Difference between pages

| Verifiedfields = changed

| Watchedfields = changed

| verifiedrevid = 464391171

| Name =

| ImageFile =

| ImageFile1 = AgI powder.jpg

| ImageFile2 = Silver-iodide-3D-balls.png

| ImageName2 = Silver iodide

| OtherNames = Argentous iodide

| IUPACName = Silver(I) iodide

| SystematicName =

| Section1 = {{Chembox Identifiers

| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}

| CASNo_Ref = {{cascite|correct|CAS}}

| EINECS = 232-038-0

| PubChem = 6432717

| Section2 = {{Chembox Properties

| Formula = AgI

| MolarMass = 234.77 g/mol

| Appearance = yellow, crystalline solid

| Odor = odorless

| Density = 5.68 g/cm³, solid<ref name=crc>Haynes, p. 4.84</ref>

| Solubility = 0.03 mg/L (20 °C)<ref name=crc/>

| SolubilityProduct = 8.52 × 10 ⁻¹⁷<ref>Haynes, p. 5.178</ref>

| =

| MeltingPt_ref = <ref name=crc/>

| BoilingPtC = 1506

| BoilingPt_ref = <ref name=crc/>

| MagSus = &minus;80.0·10⁻⁶ cm³/mol<ref>Haynes, p. 4.130</ref>

| = {{Chembox

| Structure_ref = <ref>{{cite journal|doi=10.1107/S0108768187097532|title=Anharmonic thermal vibrations in wurtzite-type AgI |year=1987 |last1=Yoshiasa |first1=A. |last2=Koto |first2=K. |last3=Kanamaru |first3=F. |last4=Emura |first4=S. |last5=Horiuchi |first5=H. |journal=Acta Crystallographica Section B: Structural Science |volume=43 |issue=5 |pages=434–440 |bibcode=1987AcCrB..43..434Y }}</ref>

| CrystalStruct = Hexagonal, [[Pearson symbol|hP4]]

| SpaceGroup = P6₃mc, No. 186

| LattConst_a = 0.4591 nm

| LattConst_c = 0.7508 nm

| LattConst_gamma = 120

| UnitCellFormulas = 2

| Dipole = 4.55 D<ref>Haynes, p. 9.65</ref>

| = {{Chembox

| Thermochemistry_ref = <ref>Haynes, p. 5.35</ref>

| DeltaHf = −61.8&nbsp;kJ·mol⁻¹

| DeltaGfree = −66.2&nbsp;kJ·mol⁻¹

| HeatCapacity = 56.8&nbsp;J·mol⁻¹·K⁻¹

| Entropy = 115.5&nbsp;J·mol⁻¹·K⁻¹

}}

| Section5 =

| Section6 =

| Section7 = {{Chembox Hazards

| ExternalSDS = [https://www.sigmaaldrich.com/US/en/sds/aldrich/204404 Sigma-Aldrich]

| GHS_ref=<ref>{{cite web |title=C&L Inventory |url=https://echa.europa.eu/information-on-chemicals/cl-inventory-database/-/discli/details/104155 |website=echa.europa.eu |access-date=15 December 2021}}</ref>

| GHSPictograms = {{GHS09}}

| GHSSignalWord = Warning

| HPhrases = {{H-phrases|410}}

| PPhrases = {{P-phrases|}}

| NFPA-H = 2

| NFPA-R = 0

| NFPA-F = 0

| FlashPt = Non-flammable

}}

'''Silver iodide''' is an [[inorganic compound]] with the formula [[Silver|Ag]][[Iodide|I]]. The compound is a bright yellow solid, but samples almost always contain impurities of metallic silver that give a grey colouration. The silver contamination arises because some samples of AgI can be highly [[Photosensitivity|photosensitive]]. This property is exploited in silver-based [[photography]]. Silver iodide is also used as an [[antiseptic]] and in [[cloud seeding]].

==Structure==

The structure adopted by silver iodide is temperature dependent:<ref>{{cite journal | last=Binner | first=J. G. P. |author2=Dimitrakis, G. |author3=Price, D. M. |author4=Reading, M. |author5= Vaidhyanathan, B. | title=Hysteresis in the β–α Phase Transition in Silver Iodine | journal=Journal of Thermal Analysis and Calorimetry | volume=84 | year=2006 | pages=409–412 | url=http://www.sump4.com/publications/paper047.pdf | doi=10.1007/s10973-005-7154-1 | issue=2 | citeseerx=10.1.1.368.2816 | s2cid=14573346 }}</ref>

*Below 420&nbsp;K, the β phase of AgI, with the [[Wurtzite (crystal structure)|wurtzite]] structure, is most stable. This phase is encountered in nature as the mineral [[iodargyrite]].

*Above 420&nbsp;K, the α phase becomes more stable. This motif is a [[body-centered cubic]] structure which has the silver centers distributed randomly between 6 octahedral, 12 tetrahedral and 24 trigonal sites.<ref>{{cite journal | last=Hull | first=Stephen | title=Superionics: crystal structures and conduction processes | journal=Rep. Prog. Phys. | volume=67 | issue=7 | year=2007 | pages=1233–1314 | url=http://stacks.iop.org/RoPP/67/1233 | doi=10.1088/0034-4885/67/7/R05 | s2cid=250874771 }}</ref> At this temperature, Ag⁺ ions can move rapidly through the solid, allowing [[fast ion conductor|fast ion conduction]]. The transition between the β and α forms represents the melting of the silver (cation) sublattice. The [[entropy of fusion]] for α-AgI is approximately half that for [[sodium chloride]] (a typical ionic solid). This can be rationalized by considering the AgI crystalline lattice to have already "partly melted" in the transition between α and β polymorphs.

*A metastable γ phase also exists below 420&nbsp;K with the [[zincblende (crystal structure)|zinc blende structure]].

[[image:Iodargyrite-263859.jpg|thumb|left|The golden-yellow crystals on this mineral sample are [[iodargyrite]], a naturally occurring form of β-AgI.]]

==Preparation and properties==

Silver iodide is prepared by reaction of an iodide solution (e.g., [[potassium iodide]]) with a solution of silver ions (e.g., [[silver nitrate]]). A yellowish solid quickly [[precipitate]]s. The solid is a mixture of the two principal phases. Dissolution of the AgI in [[hydroiodic acid]], followed by dilution with water precipitates β-AgI. Alternatively, dissolution of AgI in a solution of concentrated silver nitrate followed by dilution affords α-AgI.<ref>O. Glemser, H. Saur "Silver Iodide" in Handbook of Preparative Inorganic Chemistry, 2nd Ed. Edited by G. Brauer, Academic Press, 1963, NY. Vol. 1. p. 1036-7.</ref> Unless the preparation is conducted in dark conditions, the solid darkens rapidly, the light causing the reduction of ionic silver to metallic. The photosensitivity varies with sample purity.

==Cloud seeding==

{{Further|Cloud seeding}}

[[Image:Cessna 210 Hagelflieger Detail.jpg|thumb|left|[[Cessna 210]] equipped with a silver iodide generator for cloud seeding]]

The [[crystalline structure]] of β-AgI is similar to that of [[ice]], allowing it to induce [[freezing]] by the process known as heterogeneous [[nucleation]]. Approximately 50,000&nbsp;kg are used for [[cloud seeding]] annually, each seeding experiment consuming 10–50&nbsp;grams.<ref name=Ullmann>Phyllis A. Lyday "Iodine and Iodine Compounds" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2005. {{doi|10.1002/14356007.a14_381}}</ref> (see also [[Project Stormfury]], [[Operation Popeye]]){{cn|date=September 2023}}

==Safety==

Extreme exposure can lead to [[argyria]], characterized by localized discolouration of body tissue.<ref name="NLM-toxnet">{{cite web|title=Silver Iodide|url=http://toxnet.nlm.nih.gov/cgi-bin/sis/search/a?dbs+hsdb:@term+@DOCNO+2930|website=TOXNET: Toxicogy Data Network|publisher=U.S. National Library of Medicine|access-date=9 March 2016}}</ref>

{{clear}}

==References==

{{Reflist}}

==Cited sources==

{{Commons category|Silver iodide}}

*{{cite book |ref=Haynes| editor= Haynes, William M. | date = 2016| title = [[CRC Handbook of Chemistry and Physics]] | edition = 97th | publisher = [[CRC Press]] | isbn = 9781498754293}}

{{Iodides}}

{{Silver compounds}}

{{Authority control}}

[[Category:Metal halides]]

[[Category:Iodides]]

[[Category:Silver compounds]]

[[Category:Photographic chemicals]]

[[Category:Weather modification]]

[[Category:Antiseptics]]

[[Category:Light-sensitive chemicals]]

[[Category:Wurtzite structure type]]

[[Category:Zincblende crystal structure]]