Silver iodide

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Silver iodide
Names
IUPAC name
Silver iodide
Other names
Silver monoiodide
Silver(I) iodide
Properties
AgI
Molar mass 234.77 g/mol
Appearance Yellow crystalline solid
Odor Odorless
Density 5.675 g/cm3 (20 °C)
Melting point 558 °C (1,036 °F; 831 K)
Boiling point 1,506 °C (2,743 °F; 1,779 K)
0.0000003 g/100 ml (20 °C)
Solubility Soluble in liq. ammonia
Solubility in ammonia 531 g/100 ml (0 °C)[1]
Vapor pressure ~0 mmHg
Thermochemistry
115 J·mol−1·K−1
−62 kJ/mol
Hazards
Safety data sheet Sigma-Aldrich
Flash point Non-flammable
Lethal dose or concentration (LD, LC):
2820 mg/kg (rat, oral)
Related compounds
Related compounds
Silver(I) fluoride
Silver chloride
Silver bromide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Silver iodide is an inorganic compound with the formula AgI.

Properties

Chemical

Silver iodine will slowly decompose when exposed to light into silver metal and iodine.

2 AgI → 2 Ag + I2

Physical

Silver iodide is a bright yellow solid, but samples almost always contain impurities of metallic silver that give a gray coloration. The silver contamination arises because AgI is highly photosensitive. The compound is practically insoluble in water but more soluble in ammonia.

Availability

Silver iodide is sold by chemical suppliers. Since it's a silver compound, it's not very cheap.

It occurs naturally as the mineral iodargyrite.

Preparation

Silver iodide is extremely easy to prepare by metathesis reaction: a soluble iodide salt, like NaI is added as solution to a solution of a soluble silver salt, such as silver nitrate. Due to its extremely low solubility, silver iodide will precipitate out of the solution, and can be filtered from the resulting suspension, washed and then dried.

AgNO3 + NaI → NaNO3 + AgI

Projects

  • Make photographic paper (photography)
  • Compound collecting
  • Make rain

Handling

Safety

Extreme exposure to AgI can lead to argyria, characterized by localized discoloration of body tissue.

Storage

In closed amber glass or plastic bottles, away from light and reducing agents.

Disposal

Since silver is expensive, AgI should be recycled. This can be done by reducing the compound to Ag metal, which is then collected and stored for further uses.

References

  1. Рабинович В.А., Хавин З.Я. Краткий химический справочник. - Л.: Химия, 1977 (Rabinovich V.A., Khavin Z.Ya. A short chemical reference book. - L .: Chemistry, 1977)

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