Question

Which series of reactions correctly represents chemical relations related to iron and its compound?

• A. $Fe {->[dil. H_2SO_4]} FeSO_4 {->[H_2SO_4, O_2]} Fe_2(SO_4)_3 {->[\text{heat}]}Fe$
• B. $Fe {->[O_2, \text{heat}]} FeO {->[dil. H_2SO_4]}Fe_2(SO_4) {->[\text{heat}]} Fe$
• C. $Fe {->[Cl_2, \text{heat}]} FeCl_3 {->[\text{heat, air}]} FeCl_2 {->[Zn]}Fe$
• D. $Fe {->[O_2, \text{heat}]} FeO_4 {->[CO, 600^{\circ}C]} FeO {->[CO, 700^{\circ}C]} Fe$

Answer 1

The Correct Option is D

To identify the correct series of reactions representing the chemical relations related to iron and its compounds, let us examine each option in detail:

1. Fe \rightarrow[dil. H_2SO_4] FeSO_4 \rightarrow[H_2SO_4, O_2] Fe_2(SO_4)_3 \rightarrow[\text{heat}] Fe
   • This series starts with the reaction of iron with dilute sulfuric acid to form ferrous sulfate (FeSO_4).
   • However, the subsequent reaction of FeSO_4 with H_2SO_4 and O_2 does not convert it directly to Fe_2(SO_4)_3 as proposed without additional steps or conditions.
   • The last step where Fe_2(SO_4)_3 reverts to iron by heat is not chemically feasible.
2. Fe \rightarrow[O_2, \text{heat}] FeO \rightarrow[dil. H_2SO_4] Fe_2(SO_4) \rightarrow[\text{heat}] Fe
   • Iron reacts with oxygen and heat to form iron(II) oxide (FeO), which is correct.
   • The notation mistakenly refers to Fe_2(SO_4) instead of the correct sulfate compound Fe_2(SO_4)_3.
   • Reverting back to iron through simple heating is not a valid reaction.
3. Fe \rightarrow[Cl_2, \text{heat}] FeCl_3 \rightarrow[\text{heat, air}] FeCl_2 \rightarrow[Zn] Fe
   • Iron reacts with chlorine in the presence of heat to form ferric chloride (FeCl_3), which is valid.
   • The reduction from FeCl_3 to FeCl_2 through heating is not typical.
   • The final step claiming zinc promotes reduction to iron is incorrect under the given conditions.
4. Fe \rightarrow[O_2, \text{heat}] Fe_3O_4 \rightarrow[CO, 600^{\circ}C] FeO \rightarrow[CO, 700^{\circ}C] Fe
   • Iron reacts with oxygen and heat to form magnetite Fe_3O_4, followed by a reduction with carbon monoxide at 600°C, forming FeO.
   • Further reduction with carbon monoxide at 700°C results in metallic iron. This progression is typical for extracting iron from its oxide forms using blast furnace methods.

On reviewing the reactions, option 4 correctly depicts the chemical relations related to iron and its compounds, which involve the successive conversion of iron to oxides and eventual reduction back to metallic iron:

Fe \rightarrow[O_2, \text{heat}] Fe_3O_4 \rightarrow[CO, 600^{\circ}C] FeO \rightarrow[CO, 700^{\circ}C] Fe.