Question

project report on corrosion hand written​

Answer 1

Answer:

Topic - Corrosion

Def. - 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 and sulphates is called corrosion.

Mechanism or theory of Corrosion

The most common example of corrosion is the rusting of iron. Rust is hydrated ferric oxide, Fe2 O3 x H2O. Some other example include tarnishing of silver, development of green coating on copper and bronze etc.

Mechanism or Theory of Corrosion : The theory of corrosion can be explained by taking the example of rusting of iron. The theory is called electrochemical theory because it explains the formation of rust on the basis of the formation of electrochemical cells on the surface of metal.

The formation of rust on the basis of this theory may be explained in the following steps :

(i) The water vapours on the surface of the metal dissolve CO2 and O2 from the air. Thus the surface of the metal is covered with the solution of CO2 in water, that is carbonic acid (H2 CO3)

H2O + CO2 -------> H2 CO3

Factors which promote corrosion

The factors which promote corrosion are :

(i) Reactivity of the metal. More active metals are readily corroded.

(ii) Presence of impurities: Presence of impurities in metals enhances the chances of corrosion. Pure metals do not corrode e.g. pure iron does not rust.

(iii) Presence of air and moisture. Air and moisture accelerate corrosion. Presence of gases like SO2 and CO2 in air catalyze the process of corrosion. Iron when placed in vacuum does not rust.