Silver nitrate is possibly the most important compound of silver as it’s used in a variety of industrial, commercial, and sanitary applications. The compound is soluble in water, giving a colorless solution, but it is a white crystalline compound when pure. The AgNO3 crystals have no odor but have a bitter metallic taste and may assume grayish tinge in the presence of small amounts of organic contaminants. So a grayish tint on the white crystals is an indication that organic contaminants have changed the Ag+ ions to Ag atoms. The applications of this popular silver compound span from being a catalyst in key industrial chemical processes to being an antiseptic and antibacterial agent in hospitals.
It is also known as lunar caustic and contains three elements as shown by its chemical formula and these are silver, nitrogen, and oxygen. This inorganic compound is solid and crystalline in its pure form with a melting point of 212 degrees Celsius. Heating the substance to 440 degrees causes it to decompose. Apart from being soluble in water, it is also soluble in ethyl alcohol and glycerol and may be soluble in acetone.
Uses in Printing and Photography
Lunar caustic has been used since the 18th century and it was used first in printing during the early 1700’s. Johann Schulze, a German chemist, used the compound in printing during the 1720’s. He noticed that when a mixture of silver, nitric acid, and chalk darkens when exposed to light. Note that silver and nitric acid react to form AgNO3. This discovery of Johann Schulze led the way to the development of the science of photography. It served as one of the precursors to the succeeding technology that was known in the 20th century as film photography.
Thomas Wedgwood used the chemical in a similar fashion. He used the compound to make temporary negative prints on paper in 1802 and he was able to produce various shades of gray. Thirty three years later, a British mathematician names William Henry Fox Talbot had come up with the very first paper negative, which he successfully made by coating AgNO3 and NaCl (table salt) on paper.
It seems as though that it was in the field of printing and photography that the uses of the chemical were discovered. However, the succeeding years proved that this popular salt compound of silver has more to offer. Sometime in the late 19th century, the Greeks and Romans discovered the therapeutic benefits of the compound. They used dilute solutions of the chemical to treat wounds. It was Carl Crede that instigated the use of dilute AgNO3 solutions in treating the eyes of newborns to prevent bacterial eye infection that may result in blindness. Back in the day, this eye infection is transmitted by the mother with gonorrhea. However, this practice is no longer carried out in the modern medicine.
The compound has antimicrobial properties, although its disinfecting properties are somehow limited. A dilute solution containing this chemical is sprayed on walls in medical laboratories or facilities. It is also used on humans and you may find some topical antibacterial solutions that contain silver nitrate. This compound also plays a key role in cauterization, the process of burning skin tissue to seal wounds or remove warts.
The silver compound is used in the making of mirrors. It is mixed with sodium hydroxide, ammonia, and glucose. This solution turns silvery when cooled and coats its container and the immersed glass with a highly reflective silvery film. The substance also serves as a catalyst in the making of ethylene oxide which is used in making plastics. The compound in aqueous solution is a good medium in silver plating of plastics and metals. Small amounts of AgNO3 may be added to water, a solution which becomes a flower preservative.