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Electrochemistry

Question
CBSEENCH12006097

What is corrosion? What are the factors which affect corrosion?

Solution

Corrosion is the process of slowly eating away of the metal due to attack of the atmospheric gases on the surface of the metal resulting into the formation of compounds such as oxides, sulphides, carbonates, etc. 
The rusting of iron, tarnishing of  silver, development of green coating on copper and bronze are some of the examples of corrosion.

The main factors which affect corrosion are

Presence of water and the electrolytes present in it.
1.   More the reactivity of metal, the more will be the possibility of the metal getting corroded.

2.   The impurities help in setting up voltaic cells, which increase the speed of corrosion

3.   Presence of electrolytes in water also increases the rate of corrosion

4.   Presence of CO2 in natural water increase rusting of iron.

5.   When the iron surface is coated with layers of metals more active than iron, then the rate of corrosion is retarded.

6.   A rise in temperature (with in a reasonable limit) increases the rate of corrosion.