Inorganic Synthesis

Silver nitrate preparation

Theory:

Silver(I) nitrate AgNO3 is a silver salt that is widely used as a precusor to another silver salts. It is a white crystalline solid with low melting point (209 °C).  The compound is relatively stable when exposed to light in a solid state. When heated the compound undergoes decomposition leaving silver metal. It is also used in gravimetry or potentiometry for halide ions determination in the solutions. It is be prepared by a reaction of silver metal with concentrated/diluted nitric acid:

Ag + 2 HNO3 (concentrated) → AgNO3 + H2O + NO2
3 Ag + 4 HNO3 (diluted) → 3 AgNO3 + 2 H2O + NO

Procedure:

Silver metal (55 g, 510 mmol) was placed into 250 mL beaker and approximately 60 mL of 65% nitric acid was added. A mixture was heated for about 30 minutes until the evolution of nitrogen dioxide gas stopped and all silver metal dissolved.  Additional 50 mL of distilled water were added the solution was evaporated to the initial volume. The solution was rapidly cooled down in an ice bath and the crystals of silver nitrate were filtered off with vacuum. Yield: 64.1 %.

SN1

Silver ingot [photo: Michal Hegedus]

SN3

Silver dissolving in concentrated nitric acid [photo: Michal Hegedus]

SN2

Nitrogen dioxide gas evolution [photo: Michal Hegedus]

SN4

Pure, two times recrystallized product [photo: Michal Hegedus]

Literature: