Question

What is the formula of corrosion of Silver?

Answer 1

Hint: Corrosion is a natural process that converts a refined metal into a more chemically stable form such as oxide, hydroxide, carbonate or sulfide. It is gradual destruction of materials by chemical and electrochemical reaction with their environment.

Complete answer:
Silver is a gray-white metal that is malleable and soft. The chemical symbol for silver is $Ag$. The metal is found in lead ore, but can also be a byproduct of mining other metals like gold, copper and zinc. It is a precious metal classified alongside platinum and gold, and is the best conductor of electricity.
Silver is known to be resistant to corrosion, as it does not oxidize easily. When silver is exposed to air, a layer of silver sulfide is formed on the surface. This is known as corrosion of silver. Silver object tarnish slowly in air this is due to traces of ${H_2}S$ in air which react with $Ag$ , forming black $A{g_2}S$
Chemical reaction will be $2Ag + {O_2} \to A{g_2}O$
$A{g_2}O + {H_2}S \to A{g_2}S + {H_2}O$.
When silver is attacked by sulfur, the chemical reaction leaves the metal with a brown-black patina which does not result in much metal loss. The attack also results in black fissures and pits. The rate of pitting attack is generally slow, but can increase if a stronger acid or salts are present.
Some conversion products reduce the sulfides on the silver metal, leaving it a white color. Some preventive precautions that help to preserve silver are:
$ \bullet $ Avoid touching polish surfaces with grease and salts, as these tarnish silver.
$ \bullet $ Handle any silver product with care due to its soft nature. Silver can easily become dented when handled roughly.
$ \bullet $ Avoid using the silver in environments that have sulfur products. Sulfur corrodes the surface of silver, forming black sulfide.
$ \bullet $ Avoid storing objects made up of silver in open air as they collect dust, which in turn absorbs moisture and corrodes the metal.
$ \bullet $ Silver should be kept in a dry ventilated environment that is free from sulfurous contents.
$ \bullet $ Avoid using harsh chemicals and abrasives, as these can damage silver or deposit a layer of another metal that may damage it.
$ \bullet $ A coating may be applied, although it is not recommended. It is best to consult an expert when considering applying a coating to silver.

Note:
The affinity of Sulphur is more towards silver in comparison to oxygen so $A{g_2}S$ is formed. Silver Sulphide formation is not permanent change; it is a physical process in which a layer of silver Sulphide can be easily removed using tooth powder or a detergent.
Rust is a type of corrosion. Rusting is the oxidation of iron in the presence of air and moisture.