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 ).