Overview

Silver iodide (SILL-ver EYE-oh-dide) is a light yellow crystalline or powdery material that darkens on exposure to light. The darkening occurs because silver ions (Ag⁺; silver atoms with a positive charge) are converted to neutral silver atoms (Ag⁰) that are dark gray in color. Silver iodide is used primarily in photography and in cloud-seeding experiments.

Key Facts

Other Names:

Silver(I) iodide

Formula:

AgI

Elements:

Silver, iodine

Compound Type:

Binary salt (inorganic)

State:

Solid

Molecular Weight:

234.77 g/mol

Melting Point:

558°C (1036°F)

Boiling Point:

1506°C (2743°F)

Solubility:

Insoluble in water and organic solvents; soluble in solutions of sodium chloride, potassium chloride, and ammonium hydroxide

How It Is Made

Silver iodide occurs naturally in the mineral odargyrite (also known as iodyrite), from which it can be extracted. The compound is extracted by adding concentrated hydriodic acid (HI) to the mineral, which dissolves out the silver iodide...