Difference between revisions of "Silver iodide"
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===Physical=== | ===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. | + | 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== | ==Availability== | ||
Latest revision as of 19:31, 8 September 2022
| 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 | |
| Std molar
entropy (S |
115 J·mol−1·K−1 |
| Std enthalpy of
formation (ΔfH |
−62 kJ/mol |
| Hazards | |
| Safety data sheet | Sigma-Aldrich |
| Flash point | Non-flammable |
| Lethal dose or concentration (LD, LC): | |
| LD50 (Median dose)
|
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.
Contents
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
- ↑ 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)
