Preparation of silver nitrate and its uses

Learning objectives

After reviewing this presentation learnerwill be able to • Tell the reaction involved in the synthesis of

Silver nitrate• State uses of Silver nitrate

Silver nitrate

Silver nitrate is an inorganic compound with chemical formula AgNO3. This compound is a versatile precursor to many other silver compounds, such as those used in photography.• In solid silver nitrate, the silver ions are three-

coordinated in a trigonal planar arrangement.

Preparation of Silver nitrate

Silver nitrate can be prepared by reacting silver, such as a silver bullion or silver foil, with nitric acid.

3 Ag + 4 HNO3 → 3 AgNO3 + 2 H2O + NO

This is performed under a fume hood because of toxic nitrogen oxide(s) evolved during the reaction.

Reactions of Silver nitrate

• A typical reaction with silver nitrate is to suspend a rod of copper in a solution of silver nitrate and leave it for a few hours.• The silver nitrate reacts with copper to form hairlike

crystals of silver metal and a blue solution of copper nitrate:

• Silver nitrate also decomposes when heated:

2 AgNO3 + Cu → Cu(NO3)2 + 2 Ag

2 AgNO3 → 2 Ag + O2 + 2 NO2

Uses

a) In the laboratory:i) Test for the presence of Chlorine, Bromine and Iodine ions. Ag+ + Cl- AgCl (White precipitate) Ag+ + Br- AgBr (Pale yellow precipitate)

Ag+ + I- AgI (Yellow precipitate)

ii) Test for the presence of Carbonate, Hydroxide, Sulphide and Phosphate ions.For example: Pale Green=Carbonate, Brown=Hydroxide, Black=Sulphide.

iii) Silver Nitrate is used to test the exact salinity of Sea Water. 

iv) Silver Nitrate is used in Oil Fields to determine the amount of Chloride ions in water and drilling fluids.

b) In Photography:

• Very high purity Silver Nitrate is the starting material for all chemical based photography.

• It's not the Silver Nitrate that is light sensitive, it's the Silver Halides that matter.

• Film contains a carefully formulated coating of Silver Chloride, Silver Bromide and Silver Iodide.

• The particles are ground to extremely fine particles, then mixed with a gelatin.

• The gelatin is then rolled onto a clear acetate backing (the film base).

• This process, in it's entirety, is performed in complete darkness.

c) In Ceramics:

• Silver Nitrate is used when firing pottery in a kiln to make beautiful colours. For example: 1 gram Silver Nitrate in 50 grams Distilled Water makes a 'Silver Wash' for pottery.

d) In Manufacturing:

• Silver Plating - electroplating Silver onto a base metal such as Nickel.

• Hair Dye.• Inks, like indelible, permanent fabric marker pens.• Explosives, like Silver Fulminate, Silver Azide and Silver

Acetylide.• Pharmaceuticals. • It prevents premature shrinking or dropping of buds and

blooms, in cut flowers. (2.83% solution)• It inhibits cut flowers from making ethylene, which causes

them to ripen.

e) In Biology :

• A stain for proteins and nucleic acids.• A stain in scanning electron microscopy.