What is Corrosion Class 10

In this article, you are going to learn what is corrosion. We will also discuss the causes of corrosion, conditions necessary for corrosion and preventive methods. This topic is also related to Class 10 Science NCERT, so read it carefully.

Corrosion

The chemical process of slow eating up of the surface of metals when kept n open for a long time is called corrosion.

Corrosion is a slow process of deterioration and damage of metals due to chemical reactions with their surrounding environment.

Rusting of iron is also corrosion in which a flaky layer is formed on iron articles.

What are the causes of corrosion?

Corrosion is a slow process. It can be caused by many factors.

1.  When metals are exposed to moisture or humidity present in the environment, they begin to corrode.

2.  When metals are exposed to oxygen in the air, they undergo corrosion.

3.  Acid rain also causes corrosion.

4.  Salty water also affects metal surfaces resulting in corrosion.

Conditions necessary for corrosion

The following are the main conditions necessary for corrosion

   1.  Presence of oxygen(air)

   2.  Presence of moisture (water)

   3.  Open surface of a metal

 

Examples of corrosion

Corrosion mainly affects metals and articles made of metals. Following are the main examples of corrosion

    

    1. Rusting of iron:- When iron and iron objects are exposed to the atmosphere, they are attacked by air and moisture of the atmosphere. Gradually a brown-orange layer is formed on the surface. It is called ‘rust’. Iron turns into rust (hydrated iron). The process is known as rusting of iron.

    `4Fe  + O_2 + n.H_2O\rightarrow 2Fe_2O_3.nH_2O`

  

     So hydrated ferric oxide is called rust.

    

    2.   Black coating on silver articles due to reaction of hydrogen sulphide gas and other sulphur-containing compounds in the air.

   

   3.  When copper or articles of copper are exposed to the air, they react with carbon dioxide and moisture, a thin layer of copper carbonate is formed on their surface which is green in colour.

   

   4. When aluminium and aluminium articles are exposed to air, they react with oxygen to form a layer of aluminium oxide on the surface.

 

Methods to Prevent Corrosion

Corrosion is responsible for the decay of metals and metal objects, so they are to be prevented. Following are the methods to prevent corrosion.

   1.  Sacrificial protection

   2.  Alloying

   3.  Galvanizing

   4.  Electroplating

   

    1.  Sacrificial protection: -Rusting of iron can be prevented through this method. It is also known as sacrificial anode cathodic protection. In this method, more reactive metals like zinc or magnesium are used as a sacrificial anode and the metal that is to be protected is used as a cathode.

   

   2.  Alloying: - ‘Alloying’ is the process of making alloy. An alloy is a homogenous mixture of two or more metals or metals with non-metals. Brass, bronze and stainless steel are examples of alloys. Alloys are non-reactive.

   

   3.  Galvanizing: - Coating iron or steel with a thin layer of zinc is called ‘galvanizing’. This layer is produced by electrolytic deposition. A layer of zinc oxide is coated on an iron or steel object.

    

    4.  Electroplating:- Coating the surface with metals like tin, chromium, and nickel by electroplating is used to prevent corrosion.

 

 Related Topics

1. What happens during a chemical reaction