Corrosion
Fig. Diagrammatic representation of fuel cell o
o
Hydrogen and oxygen are bubbled using porous carbon electrodes into concentrated aqueous sodium hydroxide solution.
Finely splitted platinum or palladium metal are added to the electrodes for increasing the rate of electrode reactions.
Cathode: O2( g) + 2H2O( l) + 4e –-- > 4OH –( aq) Anode: 2H2( g) + 4OH –( aq) ⎯-- > 4H2O( l) + 4e –
o The net reaction is: 2H2( g) + O2( g) →2 H2O( l)
Corrosion
We all must have observed newly bought iron, silver or coper articles appears very shiny but with passage of time they get dull. This is due to the layer of metal oxide that develops on their surface. Rusting of iron, silver jewellery getting tarnished or copper articles getting covered by green layer. Metals react with atmospheric oxygen and produces metal oxides that are basic in nature because they react with water to form bases.
o
In case of rusting of iron, the iron reacts with the oxygen present in air and moisture and develops rust( hydrated iron( III) oxide).