Question

Which of the following processes does not involve oxidation
of iron ? [2015]
(a) Decolourization of blue CuSO₄ solutution by iron
(b) Formation of Fe(CO)₅ from Fe
(c) Liberation of H₂ from steam by iron at high temperature
(d) Rusting of iron sheets

Answer 1

Which of the following processes does not involve oxidation

of iron ? [2015]

(a) Decolourization of blue CuSO₄ solutution by iron

(b) Formation of Fe(CO)₅ from Fe

(c) Liberation of H₂ from steam by iron at high temperature

(d) Rusting of iron sheets

Answer 2

Process where no oxidation of iron is involved is - (b) Formation of Fe(CO)₅ from Fe

The formation of Fe(CO)₅ from Fe is given by the reaction -

Fe + 5CO --> Fe(CO)5

Here, Fe in reactant and product both has zero oxidation number.

In decolourization of blue CuSO₄ solutution by iron.

CuSO₄ + Fe --> FeSO₄ + Cu2+

Here, Fe in reactant has zero oxidation number which decreases on compound formation. The new oxidation number is +2.

In liberation of H₂ from steam by iron at high temperature reaction taking place is -

3Fe + 2H2O --> Fe3O4 + 2H2

In this reaction, again Fe has oxidation number zero which changes to +2.

In rusting of iron sheets, Fe reacts with oxygen in presence of moisture. The reaction is -

4Fe + 3O2 + 3H2O --> 2Fe2O3.3H2O

Here again Fe changes from zero to +2 and hence change in oxidation number occurs.