The given figure shows the corrosion of iron in atmosphere,
Fill in the blanks by choosing an appropriate option. At a particular spot of an object made of iron, $$\underline {\left( {\text{i}} \right)} $$ of iron to ferrous ion takes place and that spot behaves as $$\underline {\left( {{\text{ii}}} \right)} $$ . Electrons released at anodic spot move through the metal and go to another spot on the metal and reduce oxygen in presence of $${H^ + }.$$ This spot behaves as $$\underline {\left( {{\text{iii}}} \right)} \,$$ . The ferrous ions are further oxidised by atmospheric oxygen to ferric ions which come out as rust, $$\underline {\left( {{\text{iv}}} \right)} $$ and with further production of $$\underline {\left( {\text{v}} \right)} $$ ions.
(i)
(ii)
(iii)
(iv)
(v)
(a)
oxidation
anode
cathode
Fe2O3.xH2O
hydrogen
(b)
reduction
cathode
anode
Fe3O4
hydroxide
(c)
oxidation
cathode
anode
Fe2O3.xH2O
hydrogen
(d)
oxidation
anode
cathode
Fe2O3.H2O
ferrous
A.
(a)
B.
(b)
C.
(c)
D.
(d)
Answer :
(a)
Releted MCQ Question on Physical Chemistry >> Electrochemistry
Releted Question 1
The standard reduction potentials at $$298 K$$ for the following half reactions are given against each
$$\eqalign{
& Z{n^{2 + }}\left( {aq} \right) + 2e \rightleftharpoons Zn\left( s \right)\,\,\,\,\,\,\,\,\, - 0.762 \cr
& C{r^{3 + }}\left( {aq} \right) + 2e \rightleftharpoons Cr\left( s \right)\,\,\,\,\,\,\,\,\, - 0.740 \cr
& 2{H^ + }\left( {aq} \right) + 2e \rightleftharpoons {H_2}\left( g \right)\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,\,0.000 \cr
& F{e^{3 + }}\left( {aq} \right) + 2e \rightleftharpoons F{e^{2 + }}\left( {aq} \right)\,\,\,\,\,\,\,\,0.770 \cr} $$
which is the strongest reducing agent ?
A solution containing one mole per litre of each $$Cu{\left( {N{O_3}} \right)_2};AgN{O_3};H{g_2}{\left( {N{O_3}} \right)_2};$$ is being electrolysed by using inert electrodes. The values of standard electrode potentials in volts (reduction potentials) are :
$$\eqalign{
& Ag/A{g^ + } = + 0.80,\,\,2Hg/H{g_2}^{ + + } = + 0.79 \cr
& Cu/C{u^{ + + }} = + 0.34,\,Mg/M{g^{ + + }} = - 2.37 \cr} $$
With increasing voltage, the sequence of deposition of metals on the cathode will be :