Question
CO2 is always present in natural water. Explain its effect (increases, stops or no effect) on rusting of iron.
Solution
CO2 increases rusting of iron: CO2 present in water is in the form of H2CO3. H2CO3dissociates into H+ and HCO3-.
Hydroxyl ion or bicarbonate ions attack the iron surface to form anodic regions in which iron loses electrons and pass on to ferrous sulphate which is further oxidised to ferric state by oxygen of the air. The released electrons move towards the cathode region where H+ions are converted into hydrogen gas.
Thus CO2 increases rusting because H2CO3 gives H+ which gain electrons to form H2 gas. The electrons are released by iron.
Hydroxyl ion or bicarbonate ions attack the iron surface to form anodic regions in which iron loses electrons and pass on to ferrous sulphate which is further oxidised to ferric state by oxygen of the air. The released electrons move towards the cathode region where H+ions are converted into hydrogen gas.
Thus CO2 increases rusting because H2CO3 gives H+ which gain electrons to form H2 gas. The electrons are released by iron.
