Question

What is meant by corrosion$?$How the corrosion is caused $?$ How it can be prevented $?$ What is the effect of corrosion on:
$\left( {a.} \right)$ copper
$\left( {b.} \right)$ silver

Answer 1

Hint: Corrosion is generally eaten up by metal gradually by the atmospheric conditions. It can be caused due to many reasons which are uncertain and they can be prevented too. Corrosion has different effects on different metals. Rusting is a form of corrosion which takes place on iron.

Complete answer:
When the material comes in contact with the external environment and it reacts with this environment over a period of time then there is formation of oxide of metals which will deteriorate its structure and thus break down into smaller pieces. The whole process of eating up of the metal gradually when it comes in contact with the environment is termed as corrosion.
For better understanding of occurrence of corrosion we will see the steps:
$1.$ Firstly there will be a anionic process where the metal reacts with the surroundings and form a layer of oxides while it generate the electrons
$2.$ Secondly the cathodic process where the electrons produced in the anionic process will be consuming rapidly.
Thus these two processes are the main reasons for corrosion to take place.
Corrosion can be prevented in following ways:
$1.$ For prevention we have to cure the cause of corrosion which is the environmental factors. Keep isolated metals from the contact of environmental factors like moisture, water drops, gases and others.
$2.$ We can use various methods for the same like electroplating the metal, the sacrificial method, by oiling the surface of the metals and many more.
Corrosion has different effects on different metals depending on the oxide it formed.
$\left( {a.} \right)$ When copper is exposed to moisture and water vapours it get corroded easily. It gets oxidised and the bright copper surface begin to tarnish. After that this tarnish converts into dark brown and then finally to green. This reduces the strength of the metal.
$\left( {b.} \right)$ When silver is exposed to the environment then it gets corroded easily to form a metal sulphide which is called silver sulphide. Corrosion of silver is called roasting. The colour of silver changes into brown black.

Note:
Corrosion can be taken up very easily in any metal so to make it nonreactive we make alloys of metals. Whenever metals come in contact with the environment it gets corroded so we can prevent the metal surface from coming in contact with the environment. Corrosion is the redox reaction on the surface of metals.