Серебро иодид

Химические свойства

Yellow Crystalline Powder

Физические свойства

Light yellow hexagonal crystals or powder; darkens on exposure to light; density 5.68 g/cm³ ; melts at 558°C; vaporizes at 1,506°C; insoluble in water, most acids and ammonium carbonate solution; moderately soluble in concentrated solutions of alkali chloride, bromide, and thiosulfate; readily soluble in solutions of alkali cyanides, iodides and in hot concentrated hydriodic acid.

Использование

Silver iodide is a yellow powder formed by the combination of a soluble iodide combined with silver nitrate. Silver iodide could also be formed by exposing metallic silver to the fumes of bromine as in the daguerreotype process. This was the primary halide used for all of the 19th century camera processes until the introduction of the silver bromide gelatin plate. With the exception of the daguerreotype, all silver iodide processes relied on physical development using a reducing agent such as gallic acid, pyrogallic acid, or ferrous sulfate, an acid restrainer, and excess silver.

Подготовка

Silver iodide is prepared by adding a solution of sodium or potassium iodide to a hot solution of silver nitrate: Ag+ (aq) + Iˉ (aq) → Ag I (s) The precipitate is washed with boiling water. The preparation is done in the dark under ruby red light.

Определение

T3DB: Silver iodide is an iodide of silver. It is a photosensitive solid used in photography, as an antiseptic in medicine, and in rainmaking. Silver is a metallic element with the chemical symbol Ag and atomic number 47. It occurs naturally in its pure, free form, as an alloy with gold and other metals, and in minerals such as argentite and chlorargyrite.